Krejčl, J. (1970). Systematics, The journal of the Institute for the Comparative Study of History, Philosophy and the Science: Cultural the streams from the ice age to the 21st century. Surrey, Eng.

Krejčl, Jaroslav. Systematics, The Journal of the Institute for the Comparative Study of History, Philosophy and the Science: Cultural the Streams From the Ice Age to the 21st Century. Surrey, Eng, 1970.

Krejčl, Jaroslav. Systematics, The Journal of the Institute for the Comparative Study of History, Philosophy and the Science: Cultural the Streams From the Ice Age to the 21st Century. Surrey, Eng, 1970.