Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
enthrall, enthral (v.)
Americans spell it either way, but usually enthrall; the British spell it enthral. Both dialects spell enthralling and enthralled with two l’s (see CONSONANTS [2]). When combined with prepositions, enthrall takes either by or with: The children were enthralled by [with] her storytelling.
