• The strong Popov form of nonlinear input–output equationsBartosiewicz, Zbigniew; Pawluszewicz, Ewa; Wyrwas, Małgorzata; Kotta, Ülle; Tõnso, MarisProceedings of the Estonian Academy of Sciences2018 / p. 193–206 https://doi.org/10.3176/proc.2018.3.01 https://www.scopus.com/sourceid/11500153303 https://www.scopus.com/record/display.uri?eid=2-s2.0-85052690894&origin=inward&txGid=d88c4ecefcc3cd05ce583eb9b8cd5c04 https://jcr.clarivate.com/jcr-jp/journal-profile?journal=P%20EST%20ACAD%20SCI&year=2022 https://www.webofscience.com/wos/woscc/full-record/WOS:000443380000001