APA (7th ed.) Citation

Freudenthal, H. Mathematics observed. McGraw -Hill Book Company.

Chicago Style (17th ed.) Citation

Freudenthal, Hans. Mathematics Observed. New York: McGraw -Hill Book Company.

MLA (9th ed.) Citation

Freudenthal, Hans. Mathematics Observed. McGraw -Hill Book Company.

Warning: These citations may not always be 100% accurate.