laleh, F.Farhang, et al. “Experimental and Numerical Investigation of the Effect of Adding Silica Nanoparticles on the Behavior of Composite Polyester Resin”. International Journal of Engineering & Technology, vol. 7, no. 2.13, Apr. 2018, pp. 275-6, https://doi.org/10.14419/ijet.v7i2.13.12678.