Lang, G. Johannes. <br/><br/>
Current, voltage and resistance / 
Johannes G. Lang. 
 - Berlin :  Siemens Aktiengesellschaft,  1979. 
 - 71 p. :  ill. ;  21 cm. 
 - Programmed instruction   no.09. .
<br/><br/><label>ISBN: </label>3800947099 (pbk.) 0855015098 (pbk.)