Ballou, Donald H. <br/><br/>
Plane and spherical trignometry   
by Donald H. Ballou and Frederick H. Steen 
 - Boston  Ginn & Company  1943 
 - vi, 179p. 
<br/><br/> Donated by Prof. S. K. Chatterjee 
<br/><br/><label>Dewey Class. No.: </label>516.05244  / N43