As of July 12, the NCBI Bookshelf supports searches by MeSH (Medical Subject Headings) fields, including MeSH Major Topics [MAJR], MeSH Subheadings [SH], and MeSH Terms [MH]. Bookshelf populates these MeSH fields in its index from the MeSH assignments in the NLM Catalog.
Bookshelf now also supports searching by author supplied keywords. These keywords are indexed along with autogenerated concept phrases in the Bookshelf Concept Phrases and Keywords field [KYWD]. For more information about using these and other Bookshelf search fields, visit the Search Field Descriptions and Tags section of Bookshelf Help.