2003 — Andrew Rollings & Ernest Adams, Andrew Rollings and Ernest Adams on Game Design, New Riders Publishing (2003), →ISBN, page 526:
You might as well include this feature because if you don't, the players will create a second character that they never play with, known in MMORPG parlance as a "mule," to hold their primary avatar's things for them.
2004 — R. V. Kelly, Massively Multiplayer Online Role-Playing Games: The People, The Addiction and the Playing Experience, McFarland & Company (2004), →ISBN, page 39:
First, I took a full set of my best armor off one of my mules along with some Crystal Swords.
2007 — David L. McClard, Verotopia Online: The MMORPG of the Century, Xlibris (2007), →ISBN, page 89:
He was in the middle of organizing his massive stash of rare and exquisite bounty, all kept safely in the inventory cache of a mule, an entirely separate character which he paid a monthly fee to maintain exclusively for that purpose.
2009 — Eli Kosminsky, "Finding Adam Smith in Azeroth", in World of Warcraft and Philosophy: Wrath of the Philosopher King (eds. Luke Cuddy & John Nordlinger), Open Court Publishing (2009), →ISBN, unnumbered page:
Goods in both worlds also take up "physical" space to a certain extent, in that (ignoring mules in WoW) a player must allocate space to keep track of his or her belongings.
La faute de Marvin : avoir porté dans son ventre des capsules de cocaïne d’Amérique latine en Europe. Le temps d’un voyage, il a été une « mule », un de ces « bouletteux », comme les policiers français surnomment les transporteurs in corpore utilisés par les réseaux de trafiquants internationaux.
