Hartree, Douglas R.  1897-1958. <br/><br/>
Calculating instruments and machines / 
Douglas R. Hartree. 
 - Cambridge :  Cambridge University Press,  1950. 
 - ix, 138 p. :  ill. ;  26 cm. 
<br/><br/>Includes Index and Bibliography. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Calculators.<br/>Mathematical instruments.
<br/><br/><label>Dewey Class. No.: </label>681.145  / HAC 1950