1. Hartley, T. T., and Lorenzo, C. F., 1998, “Insights Into the Initialization of Fractional Order Operators via Semi-Infinite Lines,” NASA TM –1998-208407.
2. Lorenzo, C. F., and Hartley, T. T., 1998, “Initialization, Conceptualization, and Application in the Generalized Fractional Calculus,” NASA TP-1998-208415.
3. Hartley, T. T., and Lorenzo, C. F., 1999, “The Vector Linear Fractional Initialization Problem,” NASA TP-1999-208919.
4. Initialized Fractional Calculus;Int. J. Appl. Math.,2000
5. Lorenzo, C. F., and Hartley, T. T., 2000, “Initialized Fractional Calculus,” NASA TP –2000-209943.