Hi Michaela. Certainly feel free to use any plots or ideas you find useful. The plots were created in Mathematica. A proper citation would be:
Veisdal, J. (2013). Prime Numbers and the Riemann Zeta Function. B.Sc. thesis. University of Stavanger, Stavanger.
I would however recommend that you cite the original sources instead. If you email me (jorgen.veisdal at ntnu.no) I can send you the full thesis, which includes references.
Thanks for reading!