BT Šab 87b(11) :ריש ירחא דאייר‏ :
See the entire entry for ˀīyār n.m. Iyyar (April/May)

BT Šab 87b(11) :וריש ירחא דסיון חד בשבתא‏ : the first day of the month of Sivan is a Sunday
See the entire entry for sywn n.m. Sivan (May/June)