Ball, Robert . <br/><br/>
A Primer of Astronomy /  Textual Documents 
Robert Ball. 
 - 1st ed. / 
 - Cambridge :  At The University Press ,  1920. 
 - 222p. :  ill ;  17cm . 
<br/><br/><label>Subjects--Index Terms: </label>Astronomy G-Mathematics 
<br/><br/><label>Dewey Class. No.: </label>523.1  / B 21 P