He was born in Sofia on May 21 , 1897 , and died in Yambol on June 15 , 1945 . He was born on May 21 , 1897 , in Sofia and died on June 15 , 1945 , in Yambol . He was born on May 21 , 1897 , in Yambol and died on June 15 , 1945 , in Sofia .