Although a 30 February has indeed occurred in history, what about 31 February?
The photo below shows a tombstone from Guaymas, Mexico. It carries the inscription:
Francisco R. Lopez. Falleció el 31 de Fbro. de 1889 de 21 años de edad. Su desconsolada madre y hermano dedican a su grata memoria este recuerdo.
(That is, "Francisco R. Lopez. Died 31 February 1889 at the age of 21. His bereaved mother and brother dedicate this monument to his dear memory.")
The "Q.E.D." at the top of the inscription is probably a slightly erroneous abbreviation of Que en paz descanse; that is, "May he rest in peace".
This tombstone is a mystery to me, and I would be very grateful to anyone who can explain it. Is it a hoax? Or should it have read Enro. (January) instead of Fbro. (February)?
Photo courtesy of Isaac Martinez
Вот еще нашел. Понятия не имею, что это. Общая сумма - 365, и 28 дней в январе.
Нашел здесь: https://books.google.ru/
А здесь хорошо видно, что в немецких источниках сама связь числа и месяца начинается в 1836 году.