# MathSciNet – two small changes

There are two small new changes to MathSciNet®: Search by DOI and Sort by Number of Authors.

#### I. Search by DOI

The first tweak is the ability to search by DOI in a publications search.

In a Publication search, you have the following fourteen options for fielded search:

Author, Author Related, Title, Review Text, Journal, Institution, Series,
MSC Primary/Secondary, MSC Primary, MR Number, DOI, Reviewer,
Anywhere, References.

The newest of these is DOI.  You can now search MathSciNet by entering the DOI of a paper.  For example, if you have the DOI 10.1090/S0273-0979-1992-00266-5, entering it in the field

Make sure to put in the full DOI.  A complete DOI contains a prefix and a suffix, separated by a “/“.  Since people will often be copying and pasting DOIs into the field, we made is so that you can even put in the URL of the DOI resolver:

https://doi.org/10.1090/S0273-0979-1992-00266-5
or
https://dx.doi.org/10.1090/S0273-0979-1992-00266-5

and the search will work.  (It also works with http instead of https in the URL.)

Note:  Sometimes publishers include a “/” in the suffix, as in https://doi.org/10.1093/imrn/rns214.

The result of the search in the example is the paper by Crandall, Ishii, and Lions on viscosity solutions:

MR1118699
Crandall, Michael G.(1-UCSB)Ishii, Hitoshi(J-CHUO)Lions, Pierre-Louis(F-PARIS9-A)
User’s guide to viscosity solutions of second order partial differential equations.
Bull. Amer. Math. Soc. (N.S.) 27 (1992), no. 1, 1–67.
35J60 (35B05 35D05 35G20)

A DOI search is a specialized search, but in certain circumstances, it is very useful.

#### II.  Sort by Number of Authors

The second tweak has to do with sorting.  In a list of publications resulting from a search, you can sort the results in a variety of ways: Newest, Oldest, Citations, and now also by the number of authors on each item.  For instance, a search for items authored byPaul Erdős results in 1445 matches, which, by default, are sorted by newest first.  Clicking on the “Sort by” button near the top of the left-hand column allows you to resort the results by oldest first, by decreasing number of citations, or by increasing number of authors – labeled as “#Authors“.  In the list of Erdős publications, clicking on “Show first 100 results” allows us to display 100 matches per page.  If we resort by number of authors, we see 100 papers written by Erdős alone.  Going to the next page, we see another 100 solo papers by Erdős.  It is not until the fifth page that we see co-authored papers, starting with one written by Erdős and Diaconis (MR2126886).

We have had requests for this feature, and now it is available!