ONU, Obineke Henry; EJUKWA, Justin Odadami; NANAKA, Samuel. A comparative study of the performance of cubic and quadratic models for heptagonal spherical two-factor second-order designs based on the sum of square errors. Faculty of Natural and Applied Sciences Journal of Scientific Innovations , Port Harcourt, Nigeria, v. 4, n. 1, p. 140–148, 2023. Disponível em: https://fnasjournals.com/index.php/FNAS-JSI/article/view/129. Acesso em: 3 apr. 2025.