al 
e 
  
  
References 
v. GrUBER, O., 1930: Ferienkurs in Photogrammetrie. Stuttgart 1930. 
HarrERT, B. 1954: Some remarks concerning the theory of errors for convergent aerial 
pictures in comparison with near vertical pictures. Photogrammetrie Engineer- 
ing. Dec. 1954. 
HarrerT, B. 1954— 1955: Die grundlegenden Projektionsbeziehungen der Photo- 
grammetrie. Wissenschaftliche Zeitschrift der Techn. Hochschule, Dresden. 
Buchholtz-Heft 1954— 55. See also the Int. Archives of Photogrammetry, Vol. 
XII: 4.