File:Jan Janský, 1902.jpg

into the four types (A, B, AB, O) of the ABO blood group system. Jan Janský in 1902. Source: http://www.vlast.ic.cz/vynalezy.htm https://creativecommons

org/publicdomain/mark/1.0/PDMCreative Commons Public Domain Mark 1.0falsefalse English Prince-Bishop John V Turzon's foundational plaque at Jánský Vrch