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Lua i Stíl Chicago (17ú heag.)Vissh mashinno-elektrotekhnicheski institut "V.I. Lenin.". Nauchna Sesi︠i︡a, Posvetena Na 150-godishninata Ot Rozhdenieto Na Fridrikh Engels. Sofi︠i︡a: Institut, 1972.
Lua MLA (8ú heag.)Vissh mashinno-elektrotekhnicheski institut "V.I. Lenin.". Nauchna Sesi︠i︡a, Posvetena Na 150-godishninata Ot Rozhdenieto Na Fridrikh Engels. Institut, 1972.
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