Avances del saber  [ciencia, técnica, cultura]. 

 - 4. ed. 
 - Barcelona  Editorial Labor  1971. 
 - 2 v.  ill. (part col.) fold., col. maps. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Civilization, Modern--Addresses, essays, lectures.--1950-<br/>Encyclopedias and dictionaries , Spanish.