Crossword puzzle clue "were introduced"

TV horse introduced in 1955 ... or a Plymouth model introduced in 1956

The first ones were introduced in blonde and brunette in 1959

They were introduced on "E-Day"

Were introduced

They were introduced to Western pop music during the British Invasion

Decade when ZIP codes were introduced

1980 text adventure that introduced the line "You were eaten by a grue"

Particle physicist whose findings were first accepted by Einstein, but later were shown to be fraudulent