Mathematics observed

MLA

Freudenthal, Hans, and Stephen Rudolfer. Mathematics Observed. London: Weidenfeld, 1967.

APA

Freudenthal, H., & Rudolfer, S. (1967). Mathematics observed. London: Weidenfeld.

Chicago

Freudenthal, Hans, and Stephen Rudolfer. Mathematics Observed. London: Weidenfeld, 1967.