Skills, rules, and knowledge: signals, signs, and symbols, and other distinctions in human performance models

Rasmussen, Jens Skills, rules, and knowledge: signals, signs, and symbols, and other distinctions in human performance models 257–266 1983 IEEE Transactions on Systems, Man and Cybernetics 13 3 http://www.cs.toronto.edu/~nernst/papers/Rasmussen_-_SRK.pdf