Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
AGREEMENT OF SUBJECTS AND VERBS 2: COLLECTIVE NOUN PHRASES FOLLOWED BY PLURAL NOUNS
Proximity (attraction), notional agreement, and logic conspire here to make the verb choice plural: A number of us are going to attend. A flock of starlings were making loud conversation. But at Conversational levels the doubts of the speaker and in Edited English the stylebook’s unwavering rule that subjects and verbs must agree in number can sometimes produce the singular: A pair of hits in the bottom of the ninth usually turns the trick. Either singular or plural is Standard in such constructions, although the plural usually seems more natural and comfortable. See AGREEMENT OF SUBJECTS AND VERBS (4); ATTRACTION; NOTIONAL AGREEMENT.
