H-alpha Velocity Fields of Normal Spiral Disks
  We present H-alpha velocity fields for a sample of nearly face--on spiral galaxies observed with DensePak on the WIYN telescope. We combine kinematic inclinations and position angles measured from these data with photometric inclinations and position angles measured from I-band images to show that spiral disks are intrinsically non-circular. 
David R. Andersen, M. A. Bershady, L. S. Sparke, J. S. Gallagher III,   E. M. Wilcots, W. van Driel, D. Monnier-Ragaigne