Much of the collection of the Yorkshire Archaelogical Society was transferred to the Brotherton Library at Leeds University, and is held in Special Collections. This will be closed for refurbishment and extension from 1st June to 3rd August. It will still be possible to email them with queries.
From 3rd August to 18th December there will be a pop-up Research Centre in the Brotherton Library, open 10am to 1pm and 2pm to 4pm, Monday to Friday, and 10am to 1pm on alternate Saturdays. Please contact them at least 72 hours before your visit and let them know which items to retrieve during this period.
https://library.leeds.ac.uk/locations/libraries/brotherton