Marshall, R. B.  1867-1949. <br/><br/>
Results of spirit leveling in Pennsylvania, 1899 to 1911, inclusive. 
R.B. Marshall, chief geographer. Work done in cooperation with the state. Reprinted with corrections. 
 - Washington,  Govt. Print. Off.,  1918. 
 - 164 p.  pl.  24 cm. 
 - Geological Survey bulletin,  515 .
<br/><br/><label>LCCN: </label>gs 19000004  
<br/><br/><label>Subjects--Geographic Terms: </label><br/>Pennsylvania--Altitudes.
<br/><br/><label>LC Class. No.: </label>QE75  / .B9 no. 515