Karl Bollert

He studied in Rostock and obtained the doctorate in 1904 by writing a thesis on geometry called Über konzentrische Flächen zweiter Ordnung.

[S 2] From 1921 to 1923 he wrote several works related to the theory of relativity, including the description of uniformly accelerated frames now called Rindler coordinates,[1][2] and philosophically interpreted relativity in terms of neo-Kantianism in his book Einstein’s Relativitätstheorie und ihre Stellung im System der Gesamterfahrung (1921)[3] as well as in another article.

[4] Reviewing Bollert's book, Hans Reichenbach (1922) argued that its description of relativity is "short and good", and regarding the philosophical part he added that Bollert's introduction of "objectivation steps" is remarkable.

[S 3] Ernst Cassirer (1929) argued that Bollert showed how relativity can serve to confirm Neokantian views.

[S 5] In English language, the article "Early Philosophical Interpretations of General Relativity" in the Stanford Encyclopedia of Philosophy devotes an entire paragraph to Bollert's interpretation of Kantian a priorism and relativity theory.