Não informado. (1931). Highway research abstracts. National Research Council, Highway Research Board.
Lua i Stíl Chicago (17ú heag.)Não informado. Highway Research Abstracts. Washington: National Research Council, Highway Research Board, 1931.
Lua MLA (8ú heag.)Não informado. Highway Research Abstracts. National Research Council, Highway Research Board, 1931.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.