A user's manual for a method of map scanning and digital editing for thematicmap production and data-base construction / 
by David R. Soller ... et al. 
 - Washington, D.C. :  United States Government Printing Office,  1990 
 - 38 p. :  ill. ;  27 cm. 
 - U. S. Geological Survey circular .
<br/><br/><label>Subjects--Topical Terms: </label><br/>Digital mapping<br/>Scanning systems