Lewis, L., Brown, R. A., & Schrader, J. Y. (1999). Improving the Army planning, programming, budgeting, and execution system (PPBES): The programming phase. Rand.

Lewis, Leslie, Roger Allen Brown, and John Y. Schrader. Improving the Army Planning, Programming, Budgeting, and Execution System (PPBES): The Programming Phase. Santa Monica, Calif.: Rand, 1999.

Lewis, Leslie, et al. Improving the Army Planning, Programming, Budgeting, and Execution System (PPBES): The Programming Phase. Rand, 1999.