Petko & Dimitar Dimitrov are a Bulgarian father and son team, who have written about the pre-flood Varna civilisation which they claim existed on the then exposed Black Sea plain, however, they do not call it Atlantis by name. Their book is available, in English, online(a) as a pdf file.
Their book, The Black Sea, the Flood and the Ancient Myths, which supported much of Ryan & Pitman’s work. Unlike them, who based many of their conclusions on a study of molluscs, the Dimitrovs focused on sedimentation evidence. They also suggest that the Holocene influx into the Black Sea also triggered the Vedic Aryan migration to India(b).