11. Early work in medical sociology was conducted by sociological systems theory . 12. Urie Bronfenbrenner expanded Lewin's work in 1979 into Ecological Systems Theory . 13. This view relates to systems theory and the dynamics of a complex system. 14. In systems theory , the process of conflict escalation is modeled by positive feedback. 15. The term draws from General Systems Theory , Dialectics ( philosophy ) and Design. 16. In natural science, systems theory has been a widely used approach. 17. To achieve this goal, a social systems theory approach are combined. 18. Roland Mueller : website with about 140 chronological bibliographies, some concerning systems theory . 19. Dynamical systems theory presents itself as an alternative to computational explanations of cognition. 20. Frequency domain techniques for analysis and controller design dominate SISO control system theory .