Roper, J. S. <br/><br/>
PL/1 in easy stages :  a programmed learning textbook / 
by J. S. Roper 
 - London :  Elek Science,  1973 
 - 1 v. (various paging) :   ill. ;   22 cm. 
<br/><br/><label>ISBN: </label>023617634X 
<br/><br/><label>Subjects--Topical Terms: </label><br/>PL/1 (Computer program language)