Specifically, in the 1968 July–December records, (indexed as page 322) covers renewal registrations for authors and titles such as:
: Renewals for The Bobbsey Twins at the Ice Carnival under the pseudonym Laura Lee Hope. 322.png
While the Project Gutenberg file is the most likely "paper" or document reference, "322.png" also appears in other contexts: in the 1968 July–December records