Borggrefe, C., Thiel, A., Cachay, K. Julkaistu 2006 “...educational training...”
Hackfort, D., Birkner, H.-A. Julkaistu 2004 “...educational training...”
Horch, H-D., Niessen, C., Schütte, N. Julkaistu 2003 “...educational training...”
J. Perl Julkaistu 2001 “...educational training...”
Braun, S. Julkaistu 1999 “...educational training...”