Richard Nixon opened U.S. dialogue with China nearly 20 years ago, and the effects are still being felt - even at the gift shop of the Nixon Library & Birthplace.

The shop recently received a letter from a man in China requesting its most popular postcard, that of Presidents Nixon, Ford, Bush and Reagan together at the library inauguration."The man who sent it talked about Nixon and relations between China and the U.S.," said library spokesman Kevin Cartwright. "It was quite a letter."

"He requested that we not send the postcard in any kind of identifying envelope," said Cartwright, alluding to the recent communist crackdown on the movement for democracy in China.

The best-selling postcard records the unprecedented public gathering of four presidents. The second-best seller strikes a lighter note: It is a picture of the 37th president shaking hands with Elvis Presley in the Oval Office.