Some Korean singers gained international popularity. In 1959, the Kim Sisters went to Las Vegas and became the first Korean artist to release an album in the U.S. pop market. Their cover of "Charlie Brown" reached No.7 on the Billboard Single Chart. The Kim Sisters also appeared on TV programs and radio programs and held tours in the U.S. and Europe. They made 25 appearances on The Ed Sullivan Show—more than American stars like Patti Page and Louis Armstrong (who appeared 18 times each). The Kim Sisters, Yoon Bok-hee and Patti Kim were the first singers to debut in such countries as Vietnam and the United States. The Kim Sisters became the first Korean group to release an album in the United States. They also performed in Las Vegas. 's 1961 song "The Boy in The Yellow Shirt" was covered by French singer Yvette Giraud and was also popular in Japan.