Still being sold: https://www.amazon.com/BookFactory-Black-Inventors-Notebook-LIRPE-096-LGR/dp/B0065L5F9E/ref=sr_1_7?crid=3CT1R7Z9UK8ZW&keywords=inventors%2Bjo

Still being sold: https://www.amazon.com/BookFactory-Black-Inventors-Notebook-LIRPE-096-LGR/dp/B0065L5F9E/ref=sr_1_7?crid=3CT1R7Z9UK8ZW&keywords=inventors%2Bjournal&qid=1692206002&sprefix=inventors%2Bjournal%2Caps%2C131&sr=8-7&th=1 https://www.amazon.com/BookFactory-Black-Inventors-Notebook-... for example. Notice some of the features: pages are sewn in, so it will be obvious if one is removed, tamper-evident archival paper, space to sign each page. Paper documents I think still have the most standing as evidence. This doesn't look like size for a full notary seal but space for a witness to sign. I suppose a notary could stamp it someplace.