United States. War Department, Dictionary of Spoken Russian — §15… (1945)
“ This last differs in use from the pronoun себя, §21, in that a possessor of the first or second person who is the same as the subject is often expressed by the ordinary possessive adjective; thus, one always says он взял свою шляпу "he took his (own) hat," for он взял его шляпу means "he took his (the other man's) hat"; but one says indifferently я взял свою шляпу or я взял мою шляпу "I took my hat." ”
