HORNER, P. (1988). Earthworks P.c. Horner. Thomas Telford.
Lua i Stíl Chicago (17ú heag.)HORNER, P.C. Earthworks P.c. Horner. Thomas Telford, 1988.
Lua MLA (8ú heag.)HORNER, P.C. Earthworks P.c. Horner. Thomas Telford, 1988.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.