In 1937, the first textbooks in the then still very young field of quantum chemistry were published, both written by Hans Hellmann (1903-1938). Unlike other early works in this and closely related fields, such as the books by Pauling and Wilson (1935) or by Eyring, Walter, and Kimball (1944), Hellmann's textbooks were neither reprinted nor republished later. Considering his significant scientific achievements - including the elucidation of the nature of covalent chemical bonding (1933), the molecular virial theorem (1933), the quantum mechanical force theorem (1933, 1936/1937, now known as the Hellmann-Feynman theorem), the pseudopotential method (1934), and the theory of diabatic and adiabatic elementary reactions (1935), which was later further developed by Born and Huang - this situation can only be inadequately explained.