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Citations
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Heinrich, B., & Bugnyar, T. (2007). Just how smart are ravens? Sci Am, 296(4), 64–71.
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Neuringer, A. (2004). Reinforced variability in animals and people: implications for adaptive action. Am Psychol, 59(9), 891–906.
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Quesada, J., Kintsch, W., & Gomez, E. (2005). Complex problem-solving: a field in search of a definition? Theor Issues Ergon Sci, 6(1), 5–33.
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