Scheppach, R. C., & Woehlcke L., C. (1975). Transportation productivity. Lexington Books.
Lua i Stíl Chicago (17ú heag.)Scheppach, Raymond C., agus Carl Woehlcke L. Transportation Productivity. Lexington: Lexington Books, 1975.
Lua MLA (9ú heag.)Scheppach, Raymond C., agus Carl Woehlcke L. Transportation Productivity. Lexington Books, 1975.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.