Richards, Roy <br/><br/>
Holes, gaps and cavities :  a unit for teachers : stage 1 and 2. 

 - London :   Macdonald & Co,  1970.  
 - 80 p. :  ill. ;  24 cm. 
 - Science ;  5/13 .
<br/><br/><label>ISBN: </label>0356035549 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Science--Study and teaching (Elementary)
<br/><br/><label>Dewey Class. No.: </label>372.35