Billings, Evelyn. <br/><br/>
The Billings method  

 - New York   Random House  1980 
 - 254 p.   ill.  
<br/><br/><label>ISBN: </label>039452120X  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Natural family planning
<br/><br/><label>LC Class. No.: </label>MED RG136.5  / B53