Classes of the upper level of the ontology.
Part of:
Chusov IA, Kirillov PL, Pronyaev VG, Obysov NA, Novikov GE (2019) Ontologies and databases on thermophysical properties of nuclear reactor materials. Nuclear Energy and Technology 5(2): 145-153.
https://doi.org/10.3897/nucet.5.36476