In Batman: Arkham City (2011), you can find Harley Quinn's outfit from Batman: Arkham Asylum (2009) in Joker's Fun House, complete with Warden Sharp's ID tag. : r/GamingDetails
Batman: Arkham Knight - Harley Quinn by IvanCEs on DeviantArt
ArtStation - Batman: Arkham Knight DLC, Harley Quinn Game Model
DC Comics Batman: Arkham City Harley Quinn Costume | Hot Topic