1. H. Bouakkaz, Les polynômes orthogonaux de Laguerre-Hahn de classe zéro, Thèse de l'Univ. P. et M. Curie, Paris (1990).
2. S.S. Kim and K.H. Kwon, Generalized weights for orthogonal polynomials, Diff. Int. Eq. 4 (1991) 601–608.
3. A.M. Krall and R.D. Morton, Distributional weight functions for orthogonal polynomials, SIAM J. Math. Anal. 9 (1978) 604–626.
4. A.M. Krall, The Bessel polynomial moment problem. Acta Math. Acad. Sci. Hung. 38 (1981) 105–107.
5. P. Maroni, Le calcul des formes linéaires et les polynômes orthogonaux semi-classiques, in:Orthogonal Polynomials and their Applications. Proc. Segovia (1986), Lect. Notes in Math. 1329, eds. M. Alfaro et al. (Springer, 1988) pp. 279–290.