Estimation and mental computation :  1986 yearbook ; Harold L. Schoen, Marilyn J. Zweng. 

 - Virginia:   National Council of teachers of Mathematics.   1988 
 - 248 p. ;  24 cm. 
<br/><br/><label>ISBN: </label>0873532260 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Mathematics<br/>Problem solving<br/>Arithmetic, Mental
<br/><br/><label>Dewey Class. No.: </label>511.4