University of Oxford

David M. Shotton

Since 1st January 2018, Crossref has had a new reference distribution
policy, described at <https://www.crossref.org/reference-distribution/>.

There are three possible options for setting the reference distribution
preference from which a publisher can choose, these being 'Closed',
'Limited' and 'Open".

If the 'Closed' option is chosen, the references will only be used for
the Crossref [Cited-by
service](https://www.crossref.org/services/cited-by/), and are not
distributed via any of the other Crossref interfaces.

If the 'Limited' option is chosen, the references will additionally be
made available to Crossref metadata subscribers who have signed an
agreement for the new [Crossref Metadata APIs 'Plus'
service](https://www.crossref.org/services/metadata-delivery/plus-service/)
which also came into effect on 1st January 2018.  This is the new
Crossref default option.

If the 'Open' option is chosen, the references will be openly available
to anyone using the Crossref APIs.

Publishers will no longer be able to select the reference distribution
preference for individual publications on a case-by-case basis, but
rather the preference will be set for all publications appearing under a
particular DOI prefix, with the new default option being 'Limited'.

To date, more than 60 scholarly publishers, including most of the major
ones, have responded to the Initiative for Open Citations and have
instructed Crossref to set their references to open, as describe in a
[previous post](https://opencitations.hypotheses.org/772).


Since 1st January 2018, Crossref has had a new reference distribution policy, described at https://www.crossref.org/reference-distribution/.  There are three possible options for setting the reference distribution preference from which a publisher can choose, these being ‘Closed’, ‘Limited’ and ’Open“.  If the ‘Closed’ option is chosen, the references will only be used for the Crossref Cited-by service, and are not distributed via any of the

The new Crossref reference distribution policy

For completeness, this post, also based on analyses performed by Daniel
Ecer of eLife (<d.ecer@elifesciences.org)> on data he downloaded from
Crossref in September 2017 (Ecer, 2017), complements the two preceding
posts, and details the openness of references from scholarly publishers
other than Elsevier.

** The main conclusion is that, of the 650,093,489 references stored in
Crossref from journal articles published by publishers other than
Elsevier,** **486,041,671 ([74.76%]{style="color: #ff0000"}) are open.**

The detailed statistics derived from the Crossref data at the time of
sampling relating to **all publishers except Elsevier** are as follows:

**Number of works recorded at Crossref from publishers other than
Elsevier**

Crossref has records of 93,184,372 works with DOIs, of which 69,699,633
(74.80%) are journal articles and 23,484,739 (25.20%) are works that are
not journal articles (i.e. book chapters, proceedings articles,
datasets, etc.).

Of the 93,184,372 works, 76,795,932 (82.41%) were published
by publishers other than Elsevier.

Of the 69,699,144 journal articles, 54,440,761 (78.11%) were in journals
with publishers other than Elsevier.

Of the 23,484,739 works that are not journal articles, 22,355,171
(95.19%) were published by publishers other than Elsevier.

**Numbers of non-Elsevier works with references**

Of all 76,795,932 works with DOIs recorded in Crossref from publishers
other than Elsevier, 27,609,963 (35.95%) have accompanying references
and 49,185,969 (64.05%) lack references.

Of the 54,440,761 journal articles recorded in Crossref from publishers
other than Elsevier, 23,459,805 (43.09%) have accompanying references,
and 30,980,956 (56.91%) lack references.

Of the 22,355,171 works that are not journal articles recorded in
Crossref from publishers other than Elsevier, 4,150,158 (18.56%) have
accompanying references, and 18,205,013 (81.44%) lack references.

**Number of non-Elsevier references at Crossref**

Of the 1,075,133,743 references stored in Crossref from all works,
732,513,350 (68.13%) are from works published by publishers other than
Elsevier.

Of the 956,050,193 references stored in Crossref from journal articles,
650,093,489 (68.00%) are from journals published by publishers other
than Elsevier.

Of the 119,083,550 references stored in Crossref from works that are not
journal articles, 82,419,861 (69.21%) are from works published by
publishers other than Elsevier.

**Average numbers of references per non-Elsevier work**

The 732,513,350 non-Elsevier references stored in Crossref come from
27,609,963 works of all types with accompanying references, giving an
average of 26.53 references per work.

650,093,489 non-Elsevier references come from 23,459,805 non-Elsevier
journal articles with accompanying references, giving an average of
27.71 references per journal article.

82,419,861 non-Elsevier references come from 4,150,158 non-Elsevier
works with accompanying references that are not journal articles,
averaging 19.86 references per work.

**Proportion of non-Elsevier works that have open references**

Of the 27,598,963 non-Elsevier works of all type documented in Crossref
that have accompanying references, 18,228,221 (66.05%) have open
references.

Of the 23,459,805 non-Elsevier journal articles documented in Crossref
that have accompanying references, 17,072,801 (72.77%) have open
references.

Of the 4,139,158 non-Elsevier works documented in Crossref that are not
journal articles and that have accompanying references, 1,155,420
(27.91%) have open references.

**Proportion of non-Elsevier references that are open**

Of the 732,513,350 references stored in Crossref from all works
published by publishers other than Elsevier, 523,186,205 (71.42%) are
open, and 209,327,145 (28.58%) are not open.

Of the 650,093,489 references stored in Crossref from journal articles
published by publishers other than Elsevier, 486,041,671 (74.76%) are
open, and 164,051,818 (25.24%) are not open.

Of the 82,419,861 references stored in Crossref from works published by
publishers other than Elsevier that are not journal articles, 37,144,534
(45.07%) are open, and 45,275,327 (54.93%) are not open.

**Proportion of references which are not open that are published by
publishers other than Elsevier**

Of the 551,932,682 references from all works stored at Crossref that are
not open, 209,327,145 (37.93%) are from works published by publishers
other than Elsevier.

Of the 470,008,522 references from journal articles stored at Crossref
that are not open, 164,051,818 (34.90%) are from journal articles
published by publishers other than Elsevier.

Of the 81,924,160 references from works that are not journal articles
stored at Crossref that are not open, 45,275,327 (55.26%) are from works
published by publishers other than Elsevier.

** **

** **Details for **all publishers** combined, and for **Elsevier**
separately, are given in the two previous posts.

 

**Reference**

Ecer, D. (2017). Crossref Data Notebook. Available at
<https://elifesci.org/crossref-data-notebook>

 


For completeness, this post, also based on analyses performed by Daniel Ecer of eLife (&lt;d.ecer@elifesciences.org)&gt; on data he downloaded from Crossref in September 2017 (Ecer, 2017), complements the two preceding posts, and details the openness of references from scholarly publishers other than Elsevier.

Openness of non-Elsevier references

[Yesterday (November 23rd 2017) I was working with Daniel Ecer of eLife
(<d.ecer@elifesciences.org)> to dig some hard facts out of the analyses
he undertook on data he downloaded from Crossref in September 2017
(Ecer, 2017).  Because of its dominant position in the scholarly
publishing world, in this, the second of two related posts, I report the
results for references from works published by
Elsevier.]{style="color: #000000"}

[**These show that, of** ]{style="color: #000000"}**[all 956,050,193
references from journal articles stored at Crossref, 305,956,704
(]{style="color: #000000"}[32.00%]{style="color: #ff0000"}[) are from
journal articles published by Elsevier, none of which are in the
Crossref "Open" category, freely available for
]{style="color: #000000"}**[**others to use.**]{style="color: #000000"}

**[Put another way, of the 470,008,522 references from journal articles
stored at Crossref that are not open, 305,956,704
(]{style="color: #000000"}[65.10%]{style="color: #ff0000"}[) are from
journals published by Elsevier.]{style="color: #000000"}**

[**On behalf of I4OC, I appeal to Elsevier to join the other major
academic publishers and to submit and open all its references without
delay.**]{style="color: #000000"}

[The detailed statistics derived from the Crossref data at the time of
sampling relating to **Elsevier publications** are as
follows:]{style="color: #000000"}

[**Number of Elsevier works recorded at
Crossref**]{style="color: #000000"}

[Crossref has records of 93,184,372 works with DOIs, of which 69,699,633
(74.80%) are journal articles and 23,484,739 (25.20%) are works that are
not journal articles (i.e. book chapters, proceedings articles,
datasets, etc.).]{style="color: #000000"}

[Of the 93,184,372 works of all types, 16,388,440 (17.59%) were
published by Elsevier.]{style="color: #000000"}

[Of the 69,699,633 journal articles, 15,258,872 (21.89%) were published
in Elsevier journals.]{style="color: #000000"}

[Of the 23,484,739 works that are not journal articles, 1,129,568
(4.81%) were published by Elsevier.]{style="color: #000000"}

[**Numbers of Elsevier works with references**]{style="color: #000000"}

[Of all 16,388,440 Elsevier works with DOIs recorded in Crossref,
10,835,273 (66.12%) have accompanying references, and 5,553,167 (33.88)
lack references.]{style="color: #000000"}

[Of the 15,258,872 Elsevier journal articles recorded in Crossref,
10,212,958 (66.93%) have accompanying references, and 5,045,914 (33.07%)
lack references.]{style="color: #000000"}

[Of the 1,129,568 Elsevier works that are not journal articles recorded
in Crossref, 622,315 (55.09%) have accompanying references, and 507,253
(44.91%) lack references.]{style="color: #000000"}

[**Number of Elsevier references at Crossref**]{style="color: #000000"}

[Of the 1,075,133,743 references stored in Crossref from all works,
342,620,393 (31.87%) are from works published by
Elsevier.]{style="color: #000000"}

[Of the 956,050,193 references stored in Crossref from journal articles,
305,956,704 (32.00%) are from journals published by
Elsevier.]{style="color: #000000"}

[Of the 119,083,550 references stored in Crossref from works that are
not journal articles, 36,663,689 (30.79%) are from works published by
Elsevier.]{style="color: #000000"}

[**Average numbers of references per Elsevier
work**]{style="color: #000000"}

[The 342,620,393 Elsevier references stored in Crossref come from
10,835,273 works of all types with accompanying references, giving an
average of 31.62 references per work.]{style="color: #000000"}

[305,956,704 Elsevier references come from 10,212,958 Elsevier journal
articles with accompanying references, giving an average of 29.96
references per journal article.]{style="color: #000000"}

[36,663,689 Elsevier references come from 622,315 Elsevier works with
accompanying references that are not journal articles, averaging 58.92
references per work.]{style="color: #000000"}

[**Proportion of Elsevier works that have open
references**]{style="color: #000000"}

[Of the 10,846,273 Elsevier works of all type documented in Crossref
that have accompanying references, 417 (0.0038%) have open
references.]{style="color: #000000"}

[Of the 10,212,958 Elsevier journal articles documented in Crossref that
have accompanying references, none (0.0000%) have open
references.]{style="color: #000000"}

[Of the 633,315 Elsevier works documented in Crossref that are not
journal articles and that have accompanying references, 417 (0.0658%)
have open references.]{style="color: #000000"}

[**Proportion of Elsevier references that are
open**]{style="color: #000000"}

[Of the 342,620,393 references stored in Crossref from works of all
types published by Elsevier, 14,856 (0.0043%) are open, and 342,605,537
(99.9957%) are closed.]{style="color: #000000"}

[Of the 305,956,704 references stored in Crossref from journal articles
published by Elsevier, none (0.0000%) are open, 100% being
closed.]{style="color: #000000"}

[Of the 36,663,689 references stored in Crossref from works published by
Elsevier that are not journal articles, 14,856 (0.0405%) are open, and
36,648,833 (99.9595%) are closed.]{style="color: #000000"}

[**Proportion of references which are not open that are published by
Elsevier**]{style="color: #000000"}

[Of the 551,932,682 references from all works stored at Crossref that
are not open, 342,605,537 (62.07%) are from works published by
Elsevier.]{style="color: #000000"}

[Of the 470,008,522 references from journal articles stored at Crossref
that are not open, 305,956,704 (65.10%) are from journal articles
published by Elsevier.]{style="color: #000000"}

[Of the 81,924,160 references from works that are not journal articles
stored at Crossref that are not open, 36,648,833 (44.74%) are from works
published by Elsevier.]{style="color: #000000"}

 

[Details for all publishers combined are given in the [previous
post](https://opencitations.wordpress.com/2017/11/24/milestone-for-i4oc-open-references-at-crossref-exceed-50/)]{style="color: #000000"}[,
and those for all publishers other than Elsevier in the [following
post](https://opencitations.wordpress.com/2017/11/28/openness-of-non-elsevier-references/).]{style="color: #000000"}

 

[\[Note: As a result of further calculations undertaken by Daniel Ecer
on 27th November 2017, which are recorded in his updated Crossref Data
Notebook (Ecer, 2017), the figures in this blog have been expanded to
show the average number of references for Elsevier works submitting
references.  At the same time, very minor corrections have been made the
total numbers of works in each category, which have not altered the
percentages and main conclusions presented in this
post.\]]{style="color: #3366ff"}

 

[**Reference**]{style="color: #000000"}

[Ecer, D. (2017). Crossref data notebook. Available at
<https://elifesci.org/crossref-data-notebook>]{style="color: #000000"}

 


Yesterday (November 23rd 2017) I was working with Daniel Ecer of eLife (&lt;d.ecer@elifesciences.org)&gt; to dig some hard facts out of the analyses he undertook on data he downloaded from Crossref in September 2017 (Ecer, 2017).  Because of its dominant position in the scholarly publishing world, in this, the second of two related posts, I report the results for references from works published by Elsevier.

Elsevier references dominate those that are not open at Crossref

[Yesterday (November 23rd 2017) I was working with Daniel Ecer of eLife
(<d.ecer@elifesciences.org)> to dig some hard facts out of the analyses
he undertook on data he downloaded from Crossref in September 2017
(Ecer, 2017).  In this, the first of two related posts, I report the
results for **all publishers**.]{style="color: #000000"}

[**The analyses show that, of the 33,672,763 journal articles documented
in Crossref that have accompanying references, 17,072,801
([50.70%]{style="color: #ff0000"}) have open references, and of
the **]{style="color: #000000"}**[956,050,193 references from journal
articles stored at Crossref, 486,041,671]{style="color: #000000"}
([50.84%]{style="color: #ff0000"}[) are now classified as "Open", and
are freely available for third parties to download and use for any
purpose.]{style="color: #000000"}**

[This is a significant milestone for the Initiative for Open Citations
(I4OC, <https://i4oc.org/)>, which since early 2017 has been campaigning
for scholarly publishers to open their reference lists, and a major gain
for the world of open scholarship.]{style="color: #000000"}

[The academic community is deeply indebted to all those publishers whose
references are now open (<https://i4oc.org/#publishers)>, and to
Crossref itself (<https://www.crossref.org/)>, for making these
references freely available, providing a tremendous resource for
bibliometric analysis.]{style="color: #000000"}

[However, 51.7% of the journal articles recorded in Crossref lack
accompanying references, and of the references that *are* submitted
together with the metadata for the remaining journal articles, 49.16%
are yet not open.]{style="color: #000000"}

[**On behalf of I4OC, I strongly encourage those publishers who are not
yet submitting references to Crossref with their article metadata to
start to do so, and those other publishers who are submitting references
but have not yet made them open to open them without delay**, by sending
a message requesting this to
<support@crossref.org>.]{style="color: #000000"}

[The detailed statistics derived from the Crossref data at the time of
sampling relating to **all publishers** are as
follows:]{style="color: #000000"}

[**Works with DOIs documented at Crossref**]{style="color: #000000"}

[Crossref has records of 93,184,372 works with DOIs, of which 69,699,633
(74.80%) are journal articles and 23,484,739 (25.20%) are works that are
not journal articles (i.e. book chapters, proceedings articles,
datasets, etc.).]{style="color: #000000"}

[**Numbers of works with references**]{style="color: #000000"}

[Of all 93,184,372 works with DOIs recorded in Crossref, 38,445,236
(41.3%) have accompanying references and 54,739,136 (58.7%) lack
references.]{style="color: #000000"}

[Of the 69,699,633 journal articles recorded in Crossref, 33,672,763
(48.3%) have accompanying references, and 36,026,381 (51.7%) lack
references.]{style="color: #000000"}

[Of the 23,484,739 works that are not journal articles recorded in
Crossref, 4,772,473 (20.32%) have accompanying references, and
18,709,979 (79.68%) lack references.]{style="color: #000000"}

[**Numbers of references at Crossref**]{style="color: #000000"}

[Crossref stores 1,075,133,743 references from all 93,184,372
works.]{style="color: #000000"}

[Of these references, 956,050,193 references (88.92%) are from journal
articles, and 119,083,550 references (11.08%) are from works that are
not journal articles.]{style="color: #000000"}

[**Average numbers of references per work**]{style="color: #000000"}

[The 1,075,133,743 references stored in Crossref come from 38,445,236
works of all types with accompanying references, giving an average of
27.97 references per work.]{style="color: #000000"}

[956,050,193 references come from 33,672,763 journal articles with
accompanying references, giving an average of 28.39 references per
journal article.]{style="color: #000000"}

[119,083,550 references come from 4,772,473 works with accompanying
references that are not journal articles, averaging 24.95 references per
work.]{style="color: #000000"}

[**Proportion of works that have open
references**]{style="color: #000000"}

[Of the 38,445,236 works of all type documented in Crossref that have
accompanying references, 18,228,638 (47.41%) have open
references.]{style="color: #000000"}

[Of the 33,672,763 journal articles documented in Crossref that have
accompanying references, 17,072,801 (50.70%) have open
references.]{style="color: #000000"}

[Of the 4,772,473 works documented in Crossref that are not journal
articles and that have accompanying references, 1,155,837 (24.22%) have
open references.]{style="color: #000000"}

[**Proportion of references that are open**]{style="color: #000000"}

[Of the 1,075,133,743 references stored in Crossref from works of all
types, 523,201,061 (48.66%) are open, and 551,932,682 (51.34%) are not
open.]{style="color: #000000"}

[Of the 956,050,193 references stored in Crossref from journal articles,
486,041,671 (50.84%) are open, and 470,008,522 (49.16%) are not
open.]{style="color: #000000"}

[Of the 119,083,550 references stored in Crossref from works that are
not journal articles, 37,159,390 (31.20%) are open, and 81,924,160
(68.80%) are not open.]{style="color: #000000"}

[The majority of the references that are not yet open are from works
published by Elsevier, as detailed in the [next
post](https://opencitations.wordpress.com/2017/11/24/elsevier-references-dominate-those-that-are-not-open-at-crossref/).]{style="color: #000000"}

 

[\[Note: As a result of further calculations undertaken by Daniel Ecer
on 27th November 2017, which are recorded in his updated Crossref Data
Notebook (Ecer, 2017), the figures in this blog have been expanded to
show the average number of references for works submitting references. 
At the same time, very minor corrections have been made the total
numbers of works in each category, which have not altered the
percentages and main conclusions presented in this
post.\]]{style="color: #3366ff"}

 

[**Reference**]{style="color: #000000"}

[Ecer, D. (2017). Crossref Data Notebook. Available at
<https://elifesci.org/crossref-data-notebook>]{style="color: #000000"}


Yesterday (November 23rd 2017) I was working with Daniel Ecer of eLife (&lt;d.ecer@elifesciences.org)&gt; to dig some hard facts out of the analyses he undertook on data he downloaded from Crossref in September 2017 (Ecer, 2017).  In this, the first of two related posts, I report the results for
<strong>
 all publishers
</strong>
.  **The analyses show that, of the 33,672,763 journal articles documented in Crossref that have accompanying

Messaggi di Rogue Scholar

The new Crossref reference distribution policy

Openness of non-Elsevier references

Elsevier references dominate those that are not open at Crossref

Milestone for I4OC – open references at Crossref exceed 50%