1. Allen, R.J., Goss, V.M. and Van Woerden, H. 1973, Astron. Astrophys. 29, pp. M7.
2. Allen, R.J. und Sullivan, W.T. III 1980, Astron. Astrophys. 84, pp. 181.
3. Bosma, A. 1978, “The Distribution and Kinematics of Neutral Hydrogen in Spiral Galaxies of various Morphological Types”, Ph. D. Thesis, University of Groningen.
4. Braes, L.L.E. and Miley, G.K. 1972, Mature 237, pp. 506.
5. Bridle, A.H. and Fomalont, E.B. 1976, Astron. Astrophys. 52, pp. 107.