Hafstad, M. R., & Hafstad, G. E. (1944). Use without waste: Units on conservation. Webster Pub. Co..
Lua i Stíl Chicago (17ú heag.)Hafstad, Margaret Riggs, agus George Edwin Hafstad. Use Without Waste: Units on Conservation. St. Louis: Webster Pub. Co., 1944.
Lua MLA (8ú heag.)Hafstad, Margaret Riggs, agus George Edwin Hafstad. Use Without Waste: Units on Conservation. Webster Pub. Co., 1944.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.