hark back vs refer

hark back and refer both are verbs.

Word	Noun	Adjective	Verb	Adverb
hark back	No	No	Yes	No
refer	No	No	Yes	No

As verbs, refer is a hypernym of hark back; that is, refer is a word with a broader meaning than hark back:

Other hypernyms of hark back include denote.

hark back (verb)	refer (verb)
go back to something earlier	think of, regard, or classify under a subsuming principle or with a general group or in relation to another
	have as a meaning
	make reference to
	use a name to designate
	seek information from
	send or direct for treatment, information, or a decision
	be relevant to