Skarstrom, W. (1921). Gymnastic teaching ([2d. ed.].). American physical education association.
Lua i Stíl Chicago (17ú heag.)Skarstrom, William. Gymnastic Teaching. [2d. ed.]. Springfield, Mass.: American physical education association, 1921.
Lua MLA (8ú heag.)Skarstrom, William. Gymnastic Teaching. [2d. ed.]. American physical education association, 1921.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.