Block, G D <br/><br/>
Biological timekeeping.  [electronic resource] 

 -  Science (New York, N.Y.)  Dec 1981 
 - 1121-2 p.  digital 
<br/><br/> Publication Type: Journal Article 
<br/><br/><label>ISSN: </label>0036-8075 
<br/><br/><label>Standard No.: </label>10.1126/science.214.4525.1121  doi