The quantum hypothesis for molecules with multiple degrees of freedom; Remarks on the entropy constant of diatomic gases

An English (2024) translation by P. Marquet of 3 German papers about “Die Quantenhypothese für Molekeln mit mehreren Freiheitsgraden (The quantum hypothesis for molecules with multiple degrees of freedom)” and “Bemerkung über die Entropiekonstante zweiatomiger Gase (Remarks on the entropy constant of diatomic gases)” by Max Planck (1915,a,b,c)