Underhill, S. (1999). Twins: Steven Underhill. Gmünder.
Lua i Stíl Chicago (17ú heag.)Underhill, Steven. Twins: Steven Underhill. Berlin: Gmünder, 1999.
Lua MLA (8ú heag.)Underhill, Steven. Twins: Steven Underhill. Gmünder, 1999.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.