Birk, W. O. (1949). Structural grammar for building sentences. D.C. Heath.
Lua i Stíl Chicago (17ú heag.)Birk, William Otto. Structural Grammar for Building Sentences. Boston: D.C. Heath, 1949.
Lua MLA (9ú heag.)Birk, William Otto. Structural Grammar for Building Sentences. D.C. Heath, 1949.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.