Padé-Seminar 1983 [these notes are a preliminary edition of the written version of lectures, given at the Tagungszentrum "Honnefer Haus" in Bad Honnef during the Pade' meeting organized by the Sonderforschungsbereich 72 der Universiaet Bonn from March 7th to March 10th, 1983] (1983)
Beitr. teilw. engl., teilw. franz.