Artemkina LR, Sopilko NY, Myasnikova OY, Eremina IU, Bondarchuk NV, Shamsheev SV. The Model of Upstream Investment Portfolio in the Mature Regions. IJEEP [Internet]. 2019 Jun. 1 [cited 2024 Dec. 28];9(4):173-80. Available from: https://econjournals.net.tr/index.php/ijeep/article/view/7965