Metodologicheski osobenosti v razvitieto i prilozhenieto na kolichestvenite metodi v oblastta na istoricheskite nauki v SSSR I SASHT // [Methodological Peculiarities in the Development and the Application of Quantitative Methods in the Field of Historical Sciences in the USSR and the US] Aleksandur G. Velichkov In: "Istoricheski Pregled (Bulgaria)". Vol 35. Pp 72-79. 1980 1 theory and philosophy of historiography methodology quantitative history