Allen, C. F. 1., & Allen, C. f. 1. (1959). Railroad curves and earthwork (7th ed.). McGraw-Hill.
Lua i Stíl Chicago (17ú heag.)Allen, Calvin Francis 1851, agus Calvin francis 1851 Allen. Railroad Curves and Earthwork. 7th ed. New York: McGraw-Hill, 1959.
Lua MLA (9ú heag.)Allen, Calvin Francis 1851, agus Calvin francis 1851 Allen. Railroad Curves and Earthwork. 7th ed. McGraw-Hill, 1959.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.