Citazione Stile APA (7a Edizione)

(1971). Helping others could be fun (1. publ.). Educational Publ. Bureau.

Citazione stile Chigago Style (17a edizione)

Helping Others Could Be Fun. 1. publ. Singapore: Educational Publ. Bureau, 1971.

Citatione MLA (9a ed.)

Helping Others Could Be Fun. 1. publ. Educational Publ. Bureau, 1971.