On the Law of Distribution of Energy in the Normal Spectrum (1900, Zur Theorie des Gesetzes der Energieverteilung im Normalspectrum)

The Planck's law paper.

hermes.ffn.ub.es/luisnavarro/nuevo_maletin/Planck%20(1900),%20Distribution%20Law.pdf contains a replica of the translation present in The Old Quantum Theory by Dirk ter Haar (1967).