Tolley, H. R.  1889-1958. <br/><br/>
Tractors and horses in the winter wheat belt,  Oklahoma, Kansas, Nebraska. 
By H. R. Tolley ... and W. R. Humphries. 
 - Washington,  Govt. print off.,  1924. 
 - 60 p.  illus., map, diagrs.  23 cm. 
 - United States. Dept. of agriculture.  Department bulletin no. 1202 .
<br/><br/> Joint contribution from Bureau of public roads, Bureau of agricultural economics, Bureau of animal industry. 
<br/><br/><label>LCCN: </label>agr24000326  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Horses.<br/>Traction-engines.
<br/><br/><label>LC Class. No.: </label>S711  / .T65