mention vs cross-refer

mention is a noun but cross-refer is not a noun.

Word	Noun	Adjective	Verb	Adverb
mention	Yes	No	Yes	No
cross-refer	No	No	Yes	No

As verbs, cross-refer is a hyponym of mention; that is, cross-refer is a word with a more specific, narrower meaning than mention:

mention: make reference to
cross-refer: refer from one entry to another, as in catalogues, books, and lists

mention (noun)	cross-refer (noun)
an official recognition of merit
a remark that calls attention to something or someone
a short note recognizing a source of information or of a quoted passage

mention (verb)	cross-refer (verb)
make mention of	refer from one entry to another, as in catalogues, books, and lists
commend
make reference to