
As quoted in "Sidelight on Sports: A Baseball Star is Born" https://news.google.com/newspapers?id=d5dRAAAAIBAJ&sjid=52sDAAAAIBAJ&pg=1293%2C4057980 by Al Abrams, in The Pittsburgh Post-Gazette (June 7, 1955), p. 20
Comment: 1994 interview with Vera Clemente https://www.google.com/search?tbo=p&tbm=bks&q=%22Roberto+Enrique+Clemente%22+intitle:Remember+intitle:Roberto&num=10 confirms that Enrique was Clemente's middle name; the discrepancy in spelling is presumably due to a misunderstanding by the non-Spanish-speaking Abrams, mistaking the word "Si" for the letter c.
Other, <big><big>1950s</big></big>, <big>1955</big>