Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page Incunable:

"

A finding in 2015 brought evidence of quires, as claimed by research, possibly printed in 1444–1446 and possibly assigned to Procopius Waldvogel of Avignon, France.[citation needed]