Slipher, V. M., V. M. Slipher to Edwin Hubble, September 7, 1942, on Hubble's manuscript draft and multiple interpretations, 1942-09-07
Slipher thanks Hubble for sending him the draft of his paper on nebulae rotation and describes how he left some notes in soft pencil that Hubble could…
Hubble, Edwin, Edwin Hubble to V. M. Slipher, July 27, 1942, on the draft of his paper "The Direction of Rotation of Spiral Nebulae", 1942-07-27
Hubble sent Slipher a copy of a revised paper for possible edits, emphasizing that he would revise it again based on specific spectrographic rotations…