Rockwell, Ray Robert,  1885-  <br/><br/>
Railroad track circuits and interlocking, 

 - Scranton, Pa.,  International textbook company  [1933] 
 - v, 74, 66, 58 p.  illus., 2 fold. pl., plans (part fold.) diagrs.  20 cm. 
<br/><br/><label>LCCN: </label>34026352 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Railroads--Signaling--Block system.<br/>Railroads--Signaling--Interlocking systems.
<br/><br/><label>LC Class. No.: </label>TF630  / .R6