Materiali ot vremeto meždu kraja na kăsnija eneolit i rannata bronzova epoha, otkriti na hălma Trapezica văv Veliko Tărnovo : Materials from time between the end of the Late Eneolithic and the beginning of the Early Bronze Age found at the Trapezisa hill, Veliko Turnovo. - Elenski, Nedko (2004)