advert vs cross-refer

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

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

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

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

advert (noun)	cross-refer (noun)
a public promotion of some product or service

advert (verb)	cross-refer (verb)
make a more or less disguised reference to	refer from one entry to another, as in catalogues, books, and lists
make reference to
give heed (to)