| http://digfir-published.macmillanusa.com/calc_tutorial/calc_tutorial_15_2_015.html | Chapter 1. calc_tutorial_15_2_015
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| http://digfir-published.macmillanusa.com/calc_tutorial/calc_tutorial_15_2_015_dlap.xml | DLAP questions | 50c7690eb11c0f2b62000000 |