Regnard, C., Reynolds, J., Watson, B., Matthews, D., Gibson, L., & Clarke, C. (2007). Understanding distress in people with severe communication difficulties: Developing and assessing the Disability Distress Assessment Tool (DisDAT). Journal of Intellectual Disability Research, 51(4), 277-292. https://doi.org/10.1111/j.1365-2788.2006.00875.x