Safier, Fred
Schaum's outlines theory and problems of precalculus
McGraw-Hill, 2009
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Hackert, Adelbert F.
Elements of trigonometry
D.C. Health, 1971
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Nanney, J. Louis
Trigonometry : a skills approach, lecture version
Allyn and Bacon, 1980
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Taylor, Howard E.
Contemporary trigonometry
McGraw-Hill, 1973
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Tobey, John
Study guide to accompany Nanney and Cable's trigonometry
Allyn and Bacon, 1980
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