Roberts, W. R. W. R. (1903). On bicursal curves.
Lua i Stíl Chicago (17ú heag.)Roberts, William Ralph Westropp Rev. On Bicursal Curves. 1903.
Lua MLA (9ú heag.)Roberts, William Ralph Westropp Rev. On Bicursal Curves. 1903.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.
