Raven, J. and E. Molloy (1969). Report on Exploratory Work Carried Out Prior to Initiating a Programme of Research into Values, Attitudes and Social Structures Associated with the Development of Different Types of Society , Memorandum Series 73, Dublin: ESRI, https://www.esri.ie/publications/report-on-exploratory-work-carried-out-prior-to-initiating-a-programme-of-research-into-values-attitudes-and-social-structures-associated-with-the-development-of-different-types-of-society