Gaya APA

Wagner, J, P. (1996). The enneagram spectrum of personality styles: An introducto- ry guide. Foreword by Helen Palmer & Thomas Condon. . Portland: Portland Metamorphous Press.

Gaya MLA

Wagner, Jerome, P.. "The enneagram spectrum of personality styles: An introducto- ry guide. Foreword by Helen Palmer & Thomas Condon. ". Portland: Portland Metamorphous Press, 1996. Buku.