Laird, Wilson Morrow,  1915- <br/><br/>
The upper Devonian and lower Mississippian of southwestern Pennsylvania / 
by Wilson M. Laird. 
 - [Harrisburg :  1941] 
 - 1 p. l., 23 p. :  tables, diagrs. ;  23 cm. 
<br/><br/> At head of title: ... Commonwealth of Pennsylvania.  Dept. of internal affairs ... Topographic and geologic survey ... 
<br/><br/>"Literature survey": p. 2-4. 
<br/><br/><label>LCCN: </label>gs 41000156  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Geology--Pennsylvania.<br/>Geology, Stratigraphic--Devonian.<br/>Geology, Stratigraphic--Mississippian.
<br/><br/><label>LC Class. No.: </label>QE157  / .A293 no. 126