‘López de Sa’ is my one main (complex) surname—in three words.
If you are kind enough to refer to my work, you may want to list it under ‘L’, not ‘d’ or ‘S’, as in:
López de Sa, Dan (2015): ‘Expressing Disagreement‘, Erkenntnis 80, 153–165
(I don’t have any middle name. I have a second surname, ‘Medina’, which I don’t use for academic purposes. The situation is complex enough already. ;-))