1. Benzaghou, B., Barsky, D.: Nombres de Bell et somme de factorielles. Journal de Théorie des Nombres de Bordeaux 16, 1–17 (2004)
2. Rashedi, E., Nezamabadi, H., Saryazdi, S.: Gsa. A gravitational search algorithm. Information Sciences, 179(13): 2232–2248 (2009)
3. Amandeep, K., Charanjit, S., Amandeep, S.B.: SAR image segmentation based on hybrid PSOGSA optimisation algorithm, vol. 4, issue 9 (2014). ISSN 2248-9622
4. Lecture Notes in Computer Science;J Barrera,2009
5. Dahiya, A., Dubey, R.B.: Survey of some multilevel thresolding techniques for medical imaging, vol. 3 issue 7 (2015). ISSN 2347-3878