I just caught up with a Guardian profile of Spanish author Javier Marķas: http://books.guardian.co.uk/review/story/0,12084,1477339,00.html
It seems that some of his titles are from Shakespeare, possibly in Spanish translation, though possibly not, from the list at the foot of the article. Specifically mentioned are:
"Tomorrow in the Battle Think on Me"
"When I Was Mortal"
(both from the same speech in Richard III. The former's on your RIII page, Barbara - in Spanish - but the latter isn't)
"A Heart So White" is apparently from Macbeth, not on your site.
There's also "Dark Back of Time", adapted from "dark backward and abysm of time" in The Tempest - not sure if this counts.