Below a sample of Peka-Spritz-Papier made by Hübel & Denck in Leipzig from the article "Das Spritzverfahren in der Buchbinderei" by Paul Klein in the Buchbinderlehrling, 1928. I shared other papers using this technique by Hübel & Denck from their Monatsblätter in this earlier post.
Steifbroschure (stiffened paper binding) by Amy Borezo on Ernst Collin's Bone Folder from the 2012 Bind-O-Rama, More examples including historical ones can be found by clicking on the steifbroschure label. Just scroll down.
Amy wrote a short post on how she made the paper for Bonefolder Extras here. The second edition text of Ernst Collin's Bone Folder can also be freely downloaded laid out for binding using the link in the left sidebar.