31 Fol, A. Tăpkova-Zaimova, V. Vlahov, K. Mihailov, G. Danov, H. Čičikova, M. Tončeva, G. Popov, V. Venedikov, I. 1978 Pulpudeva Seimanes philippopolitaines de l'histoire et de la culture thrace AA.VV: Pulpudeva Sofia Editions de l'Academie Bulgare des Sciences. 2 storia, cultura, Bulgaria