The document discusses several models of organizational change including Lewin's 3-stage model of change (unfreezing, changing, and refreezing), Leavitt's model focusing on four subsystems that change can impact, and Huse's 7-stage model expanding on Lewin's model. It also discusses sources of resistance to change, types of resistance, strategies for lessening resistance like leadership and clear communication, and a 4-stage process for dealing with resistance involving understanding different people's perspectives.