. . . "Definition: An xref that defines a reference to a publication such as a book, journal article, web page, or software manual. The reference may or may not be in a database, although references to PubMed are preferred when possible. The publication should make a direct reference to the instance it is attached to.\nComment: Publication xrefs should make use of PubMed IDs wherever possible. The DB property of an xref to an entry in PubMed should use the string \"PubMed\" and not \"MEDLINE\".\nExamples: PubMed:10234245"^^ . "Definition: An xref that defines a reference to a publication such as a book, journal article, web page, or software manual. The reference may or may not be in a database, although references to PubMed are preferred when possible. The publication should make a direct reference to the instance it is attached to.\nComment: Publication xrefs should make use of PubMed IDs wherever possible. The DB property of an xref to an entry in PubMed should use the string \"PubMed\" and not \"MEDLINE\".\nExamples: PubMed:10234245"^^ . "Definition: An xref that defines a reference to a publication such as a book, journal article, web page, or software manual. The reference may or may not be in a database, although references to PubMed are preferred when possible. The publication should make a direct reference to the instance it is attached to.\nComment: Publication xrefs should make use of PubMed IDs wherever possible. The DB property of an xref to an entry in PubMed should use the string \"PubMed\" and not \"MEDLINE\".\nExamples: PubMed:10234245"^^ . . . . . . . . . .