Wells, William Firth,  1887- <br/><br/>
Airborne contagion and air hygiene :  an ecological study of droplet infections / 
William Firth Wells 
 - Cambridge, Mass. :  Harvard University Press,  1955 
 - 423 p. :  ill. ;  24 cm. 
<br/><br/> Includes index 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Communicable diseases<br/>Air--Purification