The most important early contributors to the theory of buckling of steel columns with cross sections composed of thin segments

From page 444 of the 2008 book by Kurrer:
Karl-Eugen Kurrer, The History of the Theory of Structures from Arch Analysis to Computational Mechanics, Ernst & Sohn, 2008

FIGURE 7-34 The most important figures in the development of buckling theory for steel columns:
a) Hermann Zimmermann (1845 –1935) [Schaper, 1935/1, p. 225],
b) Ernst Chwalla (1901–1960)[Beer,1960,p.223],
c) Friedrich Hartmann (1876 –1945) [Vienna TU archives],
d) Karl Jäger (1903 –1975) [picture archive of the Austrian National library, Vienna]

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