This article is very useful as it describes the different ways the term ‘science’ can be used in action research.
This grounds the practicality of action research as theory.
Levin draws on the image of the two faced Roman god Janus to show how action research is always facing in two directions simultaneously - to action and to research.
Encyclopedia of Action Research: Critical theory, John Dewey, Kurt Lewin, Philosophy of science, Phenomenology, Postmodernism, Pragmatism, Ludwig Wittgenstein.
Regarding the modalities of action research, there are rich overviews of these in the Handbook of Action Research and the Encyclopedia of Action Research