De Souto, M. S. (1985). Group travel operations manual. Delamr Pub.
Lua i Stíl Chicago (17ú heag.)De Souto, Martha Sarbey. Group Travel Operations Manual. Albany, N.Y: Delamr Pub, 1985.
Lua MLA (9ú heag.)De Souto, Martha Sarbey. Group Travel Operations Manual. Delamr Pub, 1985.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.