тяжёлая умственная недостаточность . Haridussõnastik. Eesti Keele Instituut, Sõnaveeb 2026. https://sonaveeb.ee/search/unif//har/%D1%82%D1%8F%D0%B6%D1%91%D0%BB%D0%B0%D1%8F%20%D1%83%D0%BC%D1%81%D1%82%D0%B2%D0%B5%D0%BD%D0%BD%D0%B0%D1%8F%20%D0%BD%D0%B5%D0%B4%D0%BE%D1%81%D1%82%D0%B0%D1%82%D0%BE%D1%87%D0%BD%D0%BE%D1%81%D1%82%D1%8C/1/rus (21.06.2026)