Asymmetry in Isolated, Morphologically Normal Sa Galaxies
  We have examined the morphological and dynamical HI symmetry properties of a sample of moderately inclined Sa galaxies which are classified as morphologically normal. The sample galaxies were known a prior to exhibit kinematic peculiarities ranging from warps to independent, wholly decoupled disks, and are possibly the remnants of minor mergers. We compare the asymmetry of the rotation curves to global kinematic asymmetry, and find a relationship between rotation curve asymmetry and the kinematic n=2 mode. We have also examined the kinematics of these galaxies following the discussion of Briggs (1990) and find that the warps observed in the HI disks of these galaxies deviate significantly from the simple rules for warps that commonly apply. 
David A. Kornreich, Martha P. Haynes, Katherine P. Jore and R. V. E.   Lovelace