Peterson, Roger Tory and McKenny, Margaret <br/><br/>
A field guide to wildflowers Northeastern and North-central North American / 
by Roger Tory Peterson and Margaret McKenny. 
 - Boston :  Houghton Mifflin Company,  1968. 
 - 420 p. 
 - The Peterson Field Guide Series .
<br/><br/><label>ISBN: </label>0-395-08086-X