Generalizing a realization result of B. Zimmermann and K.B. Lee to infranilmanifolds. Paul Igodt — 1984 Manuscripta mathematica
Extensions realising a faithful abstract kernel and their automorphisms. Paul Igodt; Wim Malfait — 1994 Manuscripta mathematica
On the Uniqueness of Some Affinely Flat Infra-nilmanifolds. Paul Igodt; Kyung Bai Lee — 1990 Mathematische Zeitschrift