Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
abut (v.)
The transitive verb needs no preposition but occasionally takes on following the direct object: Our property abuts the Moynihan land on the east. The intransitive verb can take any of several prepositions, but primarily on and upon: The rear of the parsonage abutted on [upon] the churchyard wall. See also CONSONANTS (2).
