De crisis onzer eeuw - Sorokin, Pitirim Aleksandrovič, 1889-1968; Blok, J. A. (Johannes Assuerus), 1876-1955; van der Hoop, J. H. (Johannes Hermanus), 1887-1950 (Deventer : Kluwer, 1950)
Keywords: Civilization -- Philosophy; Culture; History -- Philosophy