It looks like either 'Izlueta' or 'Iztueta' - both seem to be Basque surnames. I did a quick google search and 'Izlueta' gave me 17 results, 'Iztueta' gave me 107000, so the latter is much more likely...! The letter at the end is most likely an initial, either of their first name or their second surname.
Mei and David, thanks so much! It's the surname of an author and after looking in Google with the name "Iztueta" and the other information I have about him, it turns out you are right!
The cross on the "z", the "tu" like a kind of "h" and the squiggle or initial at the end really confused me a lot, LOL.