Distribution of Zeros of Certain Meromorphic Continued Fractions. Hans J. Runckel — 1973 Mathematische Annalen
Continuity on the Boundary and Analytic Continuation of Continued Fractions. Hans-J. Runckel — 1976 Mathematische Zeitschrift
Bounded analytic functions in the unit disk and the behaviour of certain analytic continued fractions near singular line. Hans-J. Runckel — 1976 Journal für die reine und angewandte Mathematik