Effects of mental training consultancy in elite sports : theoretical considerations and field studies on mental skills, mental concepts and sport performance of international level elite athletes and national level juvenile ten-pin bowlers / vorgelegt von Henricus Hubertus Petrus Maria Schuijers ; geschäftsführender Leiter J.R.Nitsch.    Köln :  Deutschen Sporthochschule,  2002 . 168s.