A profound intrinsic unity and close interlacing of general abstract and geometrical ideas with concrete and analytical results and applications and characteristic of Krein's work.
Isang napakalalim tunay pagkakaisa at ng pangkalahatang close interlacing mahirap unawain at heometriko ideya na may tunay at analytical mga resulta at mga aplikasyon at mga katangian ng Krein ng trabaho.