@book{27719,
	author = {Wickman, Frans E.},
	title = {Some graphs on the calculation of geological age,},
	publisher = {Kungl. Boktryckeriet, P.A. Norstedt & Söner,},
	year = {1939.},
	series = {[Sweden] Sveriges geologiska undersökning. Ser. c. Avhandlingar och uppsatser.},
	address = {Stockholm,}
}