Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
agenda (n.)
is now both singular and plural: These agenda have [this agenda has] been recirculated for the postponed session. The Latin plural, agenda, has been largely overwhelmed in Standard use by the English plural, agendas. Most Standard speakers would consider the Latin singular, agendum, archaic. See also FOREIGN PLURALS; HIDDEN AGENDA.
