N. Khelil. L. Djerou and A. Zerarka and M. Batouche, Improvement of Gregory's formula using Particle Swarm Optimization. journal = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology. October 2009, vol. 34(10). 850 - 852 [viewed 20 September 2024]. Available from: https://publications.waset.org/pdf/14258.