Seibel, J. (1980). A research on efficiency of vocational training centres based on empirical findings concerning students' problem-solving behaviour. German Foundation for International Development.
Lua i Stíl Chicago (17ú heag.)Seibel, Jochen. A Research on Efficiency of Vocational Training Centres Based on Empirical Findings Concerning Students' Problem-solving Behaviour. West Berlin: German Foundation for International Development, 1980.
Lua MLA (9ú heag.)Seibel, Jochen. A Research on Efficiency of Vocational Training Centres Based on Empirical Findings Concerning Students' Problem-solving Behaviour. German Foundation for International Development, 1980.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.