Wangdahl, A. (1977). Types of face-to-face contact in combination with correspondence education: A survey of the literature. Dept. of Education, University of Lund.
Lua i Stíl Chicago (17ú heag.)Wangdahl, Agneta. Types of Face-to-face Contact in Combination with Correspondence Education: A Survey of the Literature. Lund: Dept. of Education, University of Lund, 1977.
Lua MLA (8ú heag.)Wangdahl, Agneta. Types of Face-to-face Contact in Combination with Correspondence Education: A Survey of the Literature. Dept. of Education, University of Lund, 1977.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.