Muhammad, A., M. B. Idris, A. A. Ishaq, and U. A. Umar. “Using Laplace Series and Partial Integration in Valuing Environmental Assets and Estimating Green GDP”. Journal of Environmental Science and Economics, vol. 2, no. 1, Mar. 2023, pp. 55-60, doi:10.56556/jescae.v2i1.477.