What holds the proton together— Science News, September 16, 1972
An experiment … at the CERN Laboratory in Geneva … gives an important clue to structural arrangements deep within the proton…. The result hints at the existence of a new and very strong fundamental interaction — the process that holds [quarks] together inside the protons.… A number of theorists have speculated about its nature and have even proposed an intermediate particle for it called a gluon.
Update
Physicists finally found evidence for gluons in 1979, in the aftermath of electron-positron collisions at a German particle accelerator (SN: 4/21/79, p. 262). Gluons bind quarks inside protons via the
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