4Greinert,Wolf-Dietrich. The German system of vocational education: history, organization, prospects[M]Baden-Baden: Nomos Verl,-Ges., 1994:11.
5Clarke, Linda. The changing Structure and significance of apprenticeship with special reference to construction[A]. In Ainley, Patrick&Helen Rainhird (eds.). Apprenticeship: Towards a New Paradigm of Leaming [M].London:Kogan Page Limited, 1999:34.