Newtonian mechanics & gravity fully model disk galaxy rotation curves   without dark matter
  EGRET gamma-ray archival data used with GALPROP software show two ringlike structures in Milky Way Plane which roughly tally with distribution of stars ([1] & references therein). To understand fully the implications of this and similar results on detailed structure and rotation curve of especially Milky Way Disk as well as rotation curves of other galaxies as derived from spatially resolved spectroscopic data-cubes, a re-examination of the basis of the connection between mass density and rotation curve is warranted. Kenneth F. Nicholson's approach [2], which uses only Newtonian dynamics & gravity, is presented. 
Dilip G. Banhatti (School of Physics, Madurai-Kamaraj University,   Madurai, India)