Origin of phrase "aces & 8's

looking for origin of phrase aces & 8's where did it come from??
thank you
len

"Aces and eights" is known as the dead man's hand in stud poker. The phrase dates back to the murder of James Butler "Wild Bill" Hickok by Jack McCall in Deadwood, Dakota Territory on Auust 2, 1876. After he was shot in the back of the head, "the famous gunman's stiffening fingers revealed his two pair -- aces and eights."

source - "Triggernometry" by Eugene Cunningham