1. Nayfeh, A. H.: Introduction to Perturbation Techniques, J. Wiley, New York 1981.
2. Narayanan, R.: J. Eng. Math. 17 (1983) p. 223/238.
3. Narayanan, R.: Int. J. Eng. Sci. 22 (1984) Nr. 7, p. 927/938.
4. Narayanan, R.; Abasaeed, A. E.: Int. Commun. Heat Mass Transfer 12 (1985) Nr. 3, p. 287/298.
5. Vrentas, J. S.; Narayanan, R.; Agrawal, S. S.: Int. J. Heat Mass Transfer 24 (1981) Nr. 9, p. 1513/1529.