When an author's name contains something like "van der", "de la", etc, and you wish to initial the author's first/middle names (all but surname) in a reference, how do you deal with the extra words?

For example, if I wish to reference a paper by António Franco de Oliveira Falcão, would I write A.F.O. Falcão? A.F.d.O. Falcão? A.F.D.O. Falcão?