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References
<ref>German, T. P., & Defeyter, M. A. (2000). Immunity to functional fixedness in young children. Psychonomic Bulletin & Review, 7(4), 707-712. Retrieved from http://search.ebscohost.com.ezproxy.biola.edu/login.aspx?direct=true&db=psyh&AN=2001-14334-015&login.asp&site=ehost-live<ref>
<ref>Kershaw, T. C., & Ohlsson, S. (2004). Multiple causes of difficulty in insight: The case of the nine-dot problem. Journal of Experimental Psychology: Learning, Memory, and Cognition, 30(1), 3-13. doi: 10.1037/0278-7393.30.1.3<ref>
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<ref>Wiley, J. (1998). Expertise as mental set: The effects of ___domain knowledge in creative problem solving. Memory & Cognition, 24(4), 716-730. Retrieved from http://search.ebscohost.com.ezproxy.biola.edu/login.aspx?direct=true&db=psyh&AN=1998-10386-011&login.asp&site=ehost-live<ref>