United States. War Department, Dictionary of Spoken Russian — §8… (1945)
“ They are M when the name of the last letter ends in a consonant; when the name of the last letter ends in a vowel they have the gender of the noun in the full expression: for instance, ВКП [ve-ka-pe] , for Всесоюзная Коммунистическая Партя "All-Russian Communist Party," feminine because партя is feminine. ”
