The theory in which Mr Campbell was so specially interested underlies most of his more recent work on differential geometry in general, and on that particular branch of it connected with Einstein 's gravitational theory.
Ang teorya sa kung saan Mr Campbell ay kaya espesyal na interesado underlies karamihan ng kanyang mga bagong trabaho sa kaugalian geometry sa pangkalahatan, at sa partikular na sangay ng ito konektado sa Einstein 's gravitational theory.