The idea of quarks: towards restoring of historical justice

Quite a long time ago several authors (see,e.g., \cite{Der}, \cite{Pe} ) mentioned that among pioneers of the quark idea we should take into consideration one more (in addition to M. Gell-Mann and G. Zweig) author, Andr'{e} Petermann (1922 - 2011). Below we place the English translation of his little known work, originally published in French. We draw attention of the readers to the closesness of the dates: M. Gell-Mann’s paper in Phys.Letters was received 4 January 1964, the CERN preprint by G. Zweig is dated by 17 January 1964 while Petermann’s paper in Nucl.Phys. was received 30 December 1963.