Webb, Eugene <br/><br/>
Unobtrusive measures: nonreactive research in the social sciences 

 - 1a ed 
 -  New York : Rand McNally College Publishing Company,   1966 
 - 395 p;   23 cm. 
<br/><br/> Incluye bibliografía Includes bibliographical references and index 
<br/><br/>1966 
<br/><br/> Contents : Approximations to knowledge,phisical traces : erosion and acretion,archives 1: the running record,archives 2: the episodic and private record,simple observationcontrived observation : hidden hardware and control. 
<br/><br/><label>ISBN: </label>528-68694-1 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Familia - Matrimonio
<br/><br/><label>Dewey Class. No.: </label>301