Thirty days hath November,
April, June, and September,
February hath xxviii alone,
And all the rest have xxxi.
Richard Grafton (c. 1511-1572) English printer
Abridgement of the Chronicles of Englande, Vol. 8 (1562)
Noted as "A rule to knowe how many dayes every moneth in the yeare hath." The oldest known version of this mnemonic (in Latin) dates back to at 1488. See here for other examples.
