The Helios operating system / 
Perihelion Software Ltd. 
 - New York :  Prentice-Hall,  1989. 
 - 510 p. :  ill. ;  24 cm. 
<br/><br/> Includes index. 
<br/><br/><label>ISBN: </label>0133860043 
<br/><br/><label>LCCN: </label>88-36416 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Helios (Computer operating system).