Does anyone know why Erich Kretschmann didn't publish anything after his first few papers in 1915 and 1917? I thought perhaps that he perished in WWI or in the flu epidemic afterwards. However, some of the biographical sketches on the web have him living for many decades afterwards. His style was highly complex and convoluted. He probably found writing painful and difficult. However, his few papers started a debate about that status of covariance that have lasted for some 90 years, and he probably influenced Einstein's point-coincidence argument. Einstein conceded his mathematical point about the possibility of formulating any theory as covariant to him with a qualification about Newtonian mechanics that soon proved wrong. So it is surprising he wrote no more if indeed he lived many decades later.