1. Adams, R., Fournier, J.: Sobolev Spaces. Academic Press, New York (2003)
2. Badalyan, G.V.: Generalization of Legendre polynomials and some of their applications. Akad. Nauk. Armyan. SSR Izv. Fiz.-Mat. Estest. Tekhn. Nauk 8, 1–28 (1955)
3. Bakke, V.: A maximum principle for an optimal control problem with integral constraints. J. Optim. Theory Appl. 13, 32–55 (1974)
4. Belbas, S.: Iterative schemes for optimal control of Volterra integral equations. Nonlinear Anal. 37, 57–79 (1999)
5. Belbas, S.: A new method for optimal control of Volterra integral equations. Appl. Math. Comput. 189, 1902–1915 (2007)