The New Encyclopaedia Britannica  24 : Macropaedia : knowledge in depth  [Metaphysics - Norway] 
 Encyclopędia 1985 1986 1989 1990 1991 1992 1993 1994 1995 1997 1998 2002 1987 
Philip W. Goetz ed.-in-chief 
 - 15. ed. 
 - 1039 S.  zahlr. Ill., graph. Darst., Kt., Notenbeisp.