Plane and spherical trigonometry :  a tetrahedron approach / 
Millard R. Mamhot [and four others]. 
 - Manila :  Unlimited Books Library Services & Publishing Inc,  c2015. 
 - vi, 213 pges :  illustration ;  23 cm. 
<br/><br/> References: p.213. 
<br/><br/><label>ISBN: </label>9789719654056 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Trigonometry.