Porrata, Oscar Emilio <br/><br/>
Retardation in the elementary urban schools of Puerto Rico 
by Oscar Emilio Porrata. 
 - Rio Piedras, P.R.  The University  1939. 
 - 63 p.  ill.  24 cm. 
 - University of Puerto Rico bulletin  ser. X, no.1 .
<br/><br/> Thesis (M.A.)--University of Chicago, 1934. 
<br/><br/>Bibliography: p. 62-63. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Grading and marking Students<br/>Public schools--Puerto Rico.<br/>Handicapped children