Gaya APA

Kirkpatrick, D, L. (2007). Implementing the four levels : a practical guide for effective evaluatin of training programs . San Francisco: Berrett-Koehler Publishers.

Gaya MLA

Kirkpatrick, Donald, L. "Implementing the four levels : a practical guide for effective evaluatin of training programs". San Francisco: Berrett-Koehler Publishers, 2007. Buku/Printed Material.