Analysis of information sources in references of the Wikipedia article "History of tennis" in English language version.
Another significant turning point came in 1968 when the French Internationals became the first Grand Slam tournament to join the "Open"" era.
it was no longer true that tennis was a middle-class sport
'Yes, "open" tennis has come at last and Bournemouth has been entrusted with the task of a world shaking launching,' said the programme notes for the 1968 Hard Court Championships of Great Britain, which brought an end to the sport's segregation of amateur and professional players.
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: CS1 maint: unfit URL (link)Another significant turning point came in 1968 when the French Internationals became the first Grand Slam tournament to join the "Open"" era.