Hassan, O., Bonet, J., Marriott, H., & Hassan, O. (2001). An averaged nodal deformation gradient linear tetrahedral element for large strain explicit dynamic applications. Communications in Numerical Methods in Engineering, 17(8), pp. 551-561. doi:10.1002/cnm.429

Hassan, Oubay, J. Bonet, H. Marriott, and O. Hassan. "An Averaged Nodal Deformation Gradient Linear Tetrahedral Element for Large Strain Explicit Dynamic Applications." Communications in Numerical Methods in Engineering 17, no. 8 (2001): 551-561.

Hassan, Oubay, J. Bonet, H. Marriott, and O. Hassan. "An Averaged Nodal Deformation Gradient Linear Tetrahedral Element for Large Strain Explicit Dynamic Applications." Communications in Numerical Methods in Engineering 17.8 (2001): 551-561.