In several articles about curves, etc, in Minkowski spaces $\Bbb L^3$ and $\Bbb L^4$, there is
Walrave, J., Curves and surfaces in Minkowski space. Doctoral Thesis, K.U. Leuven, Fac. of Science, Leuven 1995.
as a reference, but I'm having trouble finding said thesis in the internet. Since it dates from a long time ago, I think that it might not be accesible at all. And I don't even know if the author is still alive, so I could contact him (talking to the author directly worked for me before). Does someone know where to find it? I tried Library Genesis and arXiv to no avail. Looking for it, I found these references, but that's not it. I tried looking around at the university site, but I don't know Dutch.
Is there hope for me?
I managed to send prof. Walrave an e-mail. He was very receptive and sent me
the link for his thesis. I'll leave it here, in case someone studying the subject stumble upon this post, someday.The link was broken. This one should work.