MICHALSKA, Maria. Real Nullstellensatz and sums of squares. In: KRASIŃSKI, Tadeusz; SPODZIEJA, Stanisław (eds.). Analitic and Algebraic Geometry 4. Poland: Lodz University Press,2022. p. 121–136. DOI: 10.18778/8331-092-3.10. Disponível em: https://www.press.uni.lodz.pl/index.php/wul/catalog/book/1259/chapter/3684. Acesso em: 14 feb. 2026.