@book{193309,
	author = {Коган, Петр Семенович},
	title = {Пролог :},
	publisher = {Гос. изд-во,},
	year = {1923.},
	address = {Москва ;},
	url = {http://dlib.rsl.ru/rsl01006000000/rsl01006579000/rsl01006579621/rsl01006579621.pdf}
}