• Algebraic necessary and sufficient condition for difference flatnessKaldmäe, ArvoInternational Journal of Control2021 / 8 p https://doi.org/10.1080/00207179.2021.1908598 https://www.scopus.com/sourceid/12342 https://www.scopus.com/record/display.uri?eid=2-s2.0-85103637888&origin=inward&txGid=a37883eb2fc218fb85e6f1e2e44dc548 https://jcr.clarivate.com/jcr-jp/journal-profile?journal=INT%20J%20CONTROL&year=2022 https://www.webofscience.com/wos/woscc/full-record/WOS:000636953400001