Volo's Waterdeep Enchiridion
This is a book and generally has an accompanying "Law Sheet". The Menagerie found a copy in their rooms when they stayed at The Silken Line in Session 19: The Party Goes Troll Hunting Report.
Volo's Waterdeep Enchiridion
Law Sheet of Wideberth:
Purpose
To communicate the laws of the City.
Historical Details
History
In their rooms were the Volo's Waterdeep Enchiridion and a law code sheet.
The party has real acces to it, so it's up to them if they read it.
This was found in their rooms when they stayed at The Silken Line.