When I was a medical student more than half a century ago, I had the pleasant and exciting experience of hearing the late Richard Cabot each week presenting a "Clinical-Pathological Conference." It was essentially an exercise in differential diagnosis in which he stopped at each symptom, sign, or laboratory finding and mentioned its possible importance and the common conditions in which it appears, eliminating one after another as he went along until he was left with what was generally the correct diagnosis, by exclusion. He then tried to fit the entire clinical picture into that diagnosis. This format, considerably modified, is the basis of the very popular "Case Records of the Massachusetts General Hospital," which still appear each week in the New England Journal of Medicine.
Most of my fellow students in those days generally referred to French's Index of Differential Diagnosis, which was a sort of dictionary-type alphabetic list