Jespersen, James <br/><br/>
From Sundials to Atomic Clocks   Understanding Time and Frequency 

 - 2th ed.  
 - New York  Dover Publications Inc  1999 
 - 308p 
<br/><br/> includes index and biblioraphy 
<br/><br/><label>ISBN: </label>0486409139     300 
<br/><br/><label>Dewey Class. No.: </label>N31  / J494