“…He claimed that Kelsen's theory was 'destructive and corrosive'. 22 Ten years later he published a frontal attack against Kelsen's legal theory, 23 to which the latter responded with forcefulness and derision. 24 Schwind's arguments were somewhat weak but, as Olechowski demonstrates, the normative approach to law has to be integrated into the historical and sociological research of law and not excluded from these areas.…”