Opik, Ernst Julius,  1893- <br/><br/>
Interplanetary encounters / 
by Ernst J. Opik. 
 - Amsterdam :  Elsevier Science,  1976. 
 - 155 p. ;  25 cm. 
 - Developments in solar system and space science ;  2. .
 - Developments in solar system and space science ;  2. .
<br/><br/> Includes index. 
<br/><br/>References : p. 145-147. 
<br/><br/><label>ISBN: </label>0444413715 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Mechanics, Celestial.<br/>Gravitation.<br/>Planets--Orbits.