Thanks to a tip from a reader named Raymond, I can share these images of a notebook that belonged to Albert Einstein:

“Einstein’s search for general relativity spanned eight years, 1907-1915. … sometime between the late summer of 1912, when Einstein moved from Prague to Zurich, and early 1913. … [Einstein kept a notebook that was] found among his papers when Einstein died in 1955 … a small, brown notebook containing his private calculations from just this time. This is the Zurich notebook.”

See more at : Einstein’s Zurich Notebook