Ryan, Peter <br/><br/>
Journey to the Planets / :  Explorer 1 / 
by P. Ryan, L. Pesek. 
 - Harmondsworth, Middlesex, England :  A Puffin Original / Penguin Books,  1972. 
 - 48 p. :  ill. ;  22 cm. 
<br/><br/>Index, p. 48 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Աստղագիտություն
<br/><br/><label>Subjects--Index Terms: </label>Planets