Josef Nerb Frank E. Ritter Josef Krems Knowledge level learning and the power law: A soar model of skill acquisition in scheduling. 20-29 1999 8 Kognitionswissenschaft 1 http://link.springer.de/link/service/journals/00197/bibs/9008001/90080020.htm db/journals/kognitionswissenschaft/kognitionswissenschaft8.html#NerbRK99