Hafstad, M. R., & Hafstad, G. E. (1944). Use without waste: Units on conservation. Webster Pub. Co..
Chicago Style aipamenaHafstad, Margaret Riggs, and George Edwin Hafstad. Use Without Waste: Units on Conservation. St. Louis: Webster Pub. Co., 1944.
MLA aipamenaHafstad, Margaret Riggs, and George Edwin Hafstad. Use Without Waste: Units on Conservation. Webster Pub. Co., 1944.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.