Walker, Alexander Muir. <br/><br/>
Observation and inference : an introduction to the methods of epidemiology 

 - Chestnut Hill  Epidemiology Resources Inc.,  1991 
 - v, 173p.  ill.  
<br/><br/><label>ISBN: </label>0917227077  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Epidemiology<br/>Epidemiologic Methods.
<br/><br/><label>LC Class. No.: </label>RA652.4  / .W35