1. Deng, J. L. 1989, ‘Introduction to grey system theory’, The Journal of Grey System 1(1), 1–24.
2. Liu, L. Y., Chen, Y. and Wu, L. F. 2020, ‘The damping accumulated grey model and its application’, Communications in Nonlinear Science and Numerical Simulation 95, 105665.
3. Liu, S. F., Yang, Y. J. and Forrest, J. 2017, Grey data analysis: Methods, models and applications, Springer-Verlag, Singapore.
4. Nešetřil, J. and Matoušek, J. 2009, Invitation to discrete mathematics, 2nd edn, Oxford University Press.
5. Wei, B. L., Xie, N. M. and Yang, L. 2020, ‘Understanding cumulative sum operator in grey prediction model with integral matching’, Communications in Nonlinear Science and Numerical Simulation 82, 105076.