I.C.S. reference library :  a series of textbooks prepared for the students of the International Correspondence Schools and contalning in permanent form the instruction papers, examination questions, and keys used in their various courses 

 - volúmenes 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Enseñanza por correspondencia
<br/><br/><label>LC Class. No.: </label>LC6053  / I57