@article{Sievers, author = {Sievers, E. F.}, title = {Leistung}, series = {Schultz, H. J. (Ed.): Psychologie f{\"u}r Nichtpsychologen, Stuttgart (Kreuz Verlag) 1974, pp. 221-232.}, journal = {Schultz, H. J. (Ed.): Psychologie f{\"u}r Nichtpsychologen, Stuttgart (Kreuz Verlag) 1974, pp. 221-232.}, language = {de} }