Gaya APA

Heckenbach, A, J., Colby, I, K, J. (1970). Elementary functions an approach to precalculus mathematics . USA: USA: The Macmillan; 1970..

Gaya MLA

Heckenbach, Alan, J.., Colby, I., Kegley,, J.. "Elementary functions an approach to precalculus mathematics". USA: USA: The Macmillan; 1970., 1970. Text.