أحمد مهدي صالح. Development of a reduced estimator to estimate the variance and covariance matrix with large dimensions using hyperbolic trigonometric functions - (Chemical properties of the soil of the Tigris Basin in Wasit Governorate). IJAS [Internet]. 2024 Nov. 11 [cited 2025 Jan. 18];13(52):227-45. Available from: https://mail.journals.uokerbala.edu.iq/index.php/ijas/article/view/2653