One of my all time favorite or favourite(sic) artists ever.
Here are some links to keep you busy/entertained
Make your own Metamorphosis: https://escher.ntr.nl/en/mmm
Create your own tessellations: http://www.tessellations.org/
High quality scans from Boston public library: https://www.digitalcommonwealth.org/search?f%5Bcollection_na...