@ETpro The reason why La Rochefoucauld is listed under “L” and not “D” is because we call him “La Rochefoucauld” and not “de La Rochefoucauld.” That is, we alphabetize people by how we refer to them. That’s why Beethoven goes under “B” even though his full name is Ludwig von Beethoven.”
This might seem inconsistent with the fact that Peter van Inwagen gets listed under “V,” as does Martin Van Buren, but it has to do with the fact that the prepositions of other cultures have become part of the last name in the United States. Thus we refer to these people as “van Inwagen” and “Van Buren” (in accordance with the rule stated above).
(Again, this is based on Wikipedia. The procedure is outlined here.)