This is public information.
The Runners make up the most prolific organisation in the city. Consisting mostly of freelance runners who know the city and its books like the back of their hands, and they are the ones that travellers go to when seeking a specific book. After all, when faced with a city-sized library, even the most dedicated loreseeker can have some problems finding what they’re looking for.
The organisation is run out of the Raven Wing in the Bibliographies sector. Book requests go through Madam Gaunt (who is Old but Still Sharp) and are, in turn, filtered out to the section chiefs who each manage a neighbourhood. The section chief will then spread the word that a client is looking for said book, and the first freelance runner who brings the chief the book will be paid 80% of the posted bounty.
When entering a building owned by someone else, the runner is legally obligated to pay the deed-holder 10% of the posted bounty. Deed owners cannot legally refuse a runner entry if payment is offered, though many of them do (and get away with thanks to their political clout). The remaining 10% goes into Madam Gaunt’s coffers, “for the good of the organisation”.
The best freelance runners know the books within their “territory” very intimately, and many of them form small gangs both for safety and to ensure that the books are not moved out of their territory and into another gang’s. As is to be expected, these runner gangs also often clash either for more territory or for more books.