Lapp, R. E. (1974). Matter. Time-Liffe Books.
Lua i Stíl Chicago (17ú heag.)Lapp, Ralph Eugene. Matter. New York: Time-Liffe Books, 1974.
Lua MLA (9ú heag.)Lapp, Ralph Eugene. Matter. Time-Liffe Books, 1974.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.