David Natanael Magnusson, (1925 in Nässjö, Sweden – 2017 in Lidingö, Sweden) was a Swedish psychologist. He was professor in psychology at Stockholm University from 1969 to 1992. . David Magnusson is known for several theoretical, methodological and empirical contributions to psychological science. Theoretically, he developed an approach to psychological research called holistic interactionism. The basic assumption is that each person is seen holistically, with multiple systems that interact with the environment in various unique ways.
https://en.wikipedia.org/wiki/David_Magnusson