10 ???????? - A fortress on the Danube to the west of the new. eleven '??????' ????? - Town and castle in Lower Moesia, named from the river, on the banks of which it was located (now River Osum in Bulgaria.). See. "Vizantiski Izvor ...", p. 118, n. 61. 12Probleme origin and ancient history of the Bulgarians extensive literature. Recent findings of Soviet historical science on this issue is given in the "History of Bulgaria", t.I, pp. 54-59. See also D. Angelov and M. Andreev. History on blgarskata drzhava and right. Sofia, 1955; History on Bulgaria, vol. I. Sofia, 1954, pp. 57-86.