[1] In 1971 Carl Pearcy and David Topping revisited the topic and studied commutator subspaces for Schatten ideals.
[2] As a student American mathematician Gary Weiss began to investigate spectral conditions for commutators of Hilbert–Schmidt operators.
[3][4] British mathematician Nigel Kalton, noticing the spectral condition of Weiss, characterised all trace class commutators.
[6] The following theorem is a slight extension to differences of normal operators[7] (setting B = 0 in the following gives the statement of the previous sentence).
Nigel Kalton and American mathematician Ken Dykema introduced the condition first for countably generated ideals.
[8][9] Uzbek and Australian mathematicians Fedor Sukochev and Dmitriy Zanin completed the eigenvalue characterisation.