Plane & spherical trigonometry : a tetrahedron approach 
Mamhot, Millard R. 
 -  Unlimited Books Library Services & Publishing Inc.,  2015 
 - vi, 213 p. 
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<br/><br/><label>ISBN: </label>978-9-71965405-6 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Trigonometry.
<br/><br/><label>Dewey Class. No.: </label>F 516.24 P7121 2015