Stoilov, Todor Atanasov, Stoilova, Krasimira Petrova, Vladimirov, Miroslav Dimitrov Financial Investments by Portfolio Optimization,
Technical Univ. of Sofia.Plovdiv Branch, 2019, pp. 115-130. - (Ser. Mater. Sci. Eng.), ISSN 1757-8981 (print) ; 1757-899X (online).