Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
kind of a, sort of a
These qualifiers are used with nouns, as in What kind of a dog is that? Do you have this sort of a material? and with adjectives, as in I have sort of a bad back; She has kind of a yearning to go home. In the adverbial use with adjectives, these locutions are Conversational and Informal. In the use with nouns they are Standard, although conservative usage prefers omission of the a, as in What kind of dog is that? Do you have this sort of material? especially in Formal and Oratorical contexts.
