1. Hopf Algebras;Abe,1977
2. Coproper coalgebras;Allen;J. Algebra,1978
3. B. Drabant, A. Van Daele, Pairing and the quantum double of multiplier Hopf algebras, K. U. Leuven, 1996
4. Discrete quantum groups. I. The Haar measure;Effros;Internat. J. Math.,1994
5. An associative orthogonal bilinear form for Hopf algebras;Larson;Amer. J. Math.,1969