Probing levels of life :  a laboratory manual / 
Paul J. Hummer ... et al. 
 - Columbia, Ohio :  Charles E. Merrill,  1973. 
 - 232 p. :  ill. ;  28 cm. 
<br/><br/><label>ISBN: </label>7067570260 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Biology--Laboratory manuals.