Hi XXXXXXXX,
You have an amazing find! As far as the Hilter book with drawings etc. if you are not interested in selling them, I'd contact the Smithsonian in D.C to ask if they'd like the copy you have. They also handle exhibits and can offer or can inform you as to where your Petre work might be best suited.They may want that also!
you can contact them at the following link I am providing.
goSmithsonian | Contact Us
If there is anything further I can help you with, please feel free to ask.
Regards and congratulations on your find!
~Dee
Research Specialist
35 yrs in Art Industry, Gallery owner, Illustrator, Designer, Teacher, Private Firm Researcher