Harder, Theodor. <br/><br/>
Introduction to mathematical models in market and opinion research with practical procedures, and estimates of computing requirements / 
Theodor Harder. 
 - Holland:  D. Reidel Publishing,  1969. 
 - ix, 194 p. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Market research--Mathematical models.