Liubomir Chakalov (1886-1963)

Ljubomir Chakaloff at Wikipedia.

Ljubomir Tschakaloff at Mathematics Genealogy Project.

Short Biography from L. Tchakalov, Opera, Bulg. Acad. Sci., 1982

Bojanov, B. D.,Lubomir Tschakaloff (1886-1963), Serdica Mathematical Journal 33 (2007), iii-iv.