Geer,Helen Thornton  <br/><br/>
Charging systems / 
Helen Thornton Geer 
 - Chicago  :  American Library Association ,  1955. 
 - xii, 177 pages :  ill. ;  21 cm. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Charging systems (Libraries)
<br/><br/><label>Dewey Class. No.: </label>025.6  / GEC 1955