Finding MODS Records for Editions
To see if a MODS record already exists for a book to be cataloged, the Library of Congress (LC) Catalog is a good place to start, since all bibliographic records include links to full MODS records that can be downloaded. Each bibliographic record within the LC Catalog (links currently located on the middle left of the screen) allows the downloading of metadata for the record in multiple formats, including MODS. Consider below the record for a 19th century Teubner edition of Aelian.
Clicking on the MODS records link allows the user to download a MODS file for the bibliographic record in question.
If there is no bibliographic record for your edition in the LC catalog, another possibility is to find a source for a MARCXML record for a book and then use the LC’s XSLT stylesheet to convert it to MODS. For example, if a digitized copy of a book is available at the Internet Archive (such as Volume 2 of the Aelian series used as the example above), a MARCXML record can be downloaded from the main page for the volume, where it says "Full Catalog Record: MARCXML."
If no MARCXML or MODS record can be found using either of these or other bibliographic sources, then a MODS record will needs to be created. A commented MODS record template has been developed to assist in creating records for these editions. OCLC's Worldcat.org is typically used to verify and in some cases create additional bibliographic information.