... It assumes a cylindrical model of the rotation of PNe, it means that the rotation velocity of any PN depends only on its distance to the rotation axis of the Milky Way and does not depend on its height over the Galacticplane. ...
... V.S. "A study of interstellar matter in the Galaxy with multicolor photometric surveys" 2009, in Abstract Book XXVII IAU General Assembly, Special Session 8, The GalacticPlane -- in Depth and Across the Spectrum, Rio de Janeiro, Aug 2009, SpS8, 505 ...