Complex sentence: Here are improved citations for the first four sources identified at Exchange paradox (footnotes 1-4), which are those NOT among the dozens of sources identified in Two Envelopes "Notes and References", "Further Reading", and "External Links".
Split into simpler sentences: Here are improved citations for the first four sources identified at Exchange paradox. These four sources are the ones NOT among dozens identified in Two Envelopes "Notes and References", "Further Reading", and "External Links".