The DP 1 Double Projector, a stereoplotter of Il b order 
by Dr.-Ing. M. AunEN» and Dipl.-Ing. G. DREYER, Oberkochen 
Translation of paper published in "Bildmessung und Luftbildwesen?^' No. 1/1968, pages 16 - 22 
Herbert Wichmann Verlag GmbH, 75 Karlsruhe 21, Rheinstraße 122