2020 J. Grumbach & D. Thomas, "Integration Principles for Complex Systems," Wiley Systems Engineering, SYS-20-018.R2, September 2020. https://doi.org/10.1002/sys.21554 J. Kolligs & D. Thomas, "The Origins and Evolution of Requirements in Engineering," IEEE Systems Journal, June 2020. DOI: 10.1109/JSYST.2020.2999557 N. Morris & D. Thomas, "Stay cool – Alternatives for Long Term Storage of Large Quantities of Liquid Hydrogen on a Mars Transfer Vehicle", *Nuclear Technology*, December 2020. https://doi.org/10.1080/00295450.2020.1819157 D. Nikitaev & D. Thomas, "Seeded Hydrogen in Mars Transfer Vehicles Using Nuclear Thermal Propulsion," AIAA Journal of Spacecraft and Rockets, July 2020. https://doi.org/10.2514/1.A34722 D. Nikitaev & D. Thomas, "Seeded Hydrogen in Nuclear Thermal Propulsion Engines," AIAA Journal of Spacecraft and Rockets, April 2020. https://doi.org/10.2514/1.A34711 D. Thomas & E. Patterson, E., Systems Modeling Language viewpoint utilization to facilitate shared mental models among system stakeholders. Systems Research and Behavioral Science, 37(1), 2020, pp.128-140. https://doi.org/10.1002/sres.2610 2019 A. Aueron, D. Thomas, & J. Cassibry, "Analytical Modeling of Radiation Attenuation and Heat Deposition in Propellant for Nuclear Thermal Rockets," AIAA Journal of Spacecraft and Rockets, March 2019. https://doi.org/10.2514/1.A34389