• Generalized observer forms for discrete-time nonlinear systemsKaldmäe, Arvo; Kotta, Ülle; Kaparin, Vadim; Mullari, Tanel; Tõnso, Maris; Pawluszewicz, EwaProceedings of the Estonian Academy of Sciences2026 / p. 137-148 https://doi.org/10.3176/proc.2026.2.05
• Transforming state equations into the generalized observer form : comparison of algebraic and differential geometric approachesKotta, Ülle; Mullari, Tanel; Tõnso, MarisProceedings of the Estonian Academy of Sciences2025 / p. 473-486 https://doi.org/10.3176/proc.2025.4.01