Here's a story from the Washington Post, with an excerpt below in case that article goes offline:

Yankees' Wells Throws Perfect Game

By Ronald Blum
AP Sports Writer
Sunday, May 17, 1998; 4:39 p.m. EDT

NEW YORK - David Wells, who stalked off the mound after a bad outing earlier this month, pitched only the 15th perfect game in major league history as the New York Yankees beat the Minnesota Twins 4-0 Sunday.

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Wells began the game with a 5.23 ERA, and his consistency was certainly in question. On May 6 in Texas, he nearly blew a 9-0 lead and tersely flipped the ball to manager Joe Torre when he was lifted in an eventual 15-13 win.

But Wells bounced back last Tuesday against Kansas City, winning 3-2. He retired his last 10 with the perfect game, he's now retired 37 consecutive batters.

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(c) Copyright 1998 The Associated Press