Methods and techniques of research 
Sanchez, Custodiosa Ancheta. 
 - revised edition. 
 -  Rex Book Store.  1986 
 - xiii, 229 pages. 
<br/><br/>
<br/><br/><label>ISBN: </label>9-71230355-1 
<br/><br/><label>Dewey Class. No.: </label>F 001.42 Sa5m 1986