In 1957 Korea introduced the first of its Christmas and New Year stamps and souvenir sheets. These were quite attractive and colourful. They also appealed to children stamp collectors and in fact, this is why I started to collect Korean stamps when I was a child. I loved the little colourful souvenir sheets. The individual stamps of the 1957 set are common and easy to find. However, the three souvenir sheets are quite rare and valuable for this first year of the Christmas and New Year issue.
The Scott Catalog gives these 1957 issues the catalog numbers of 265-67, and the souvenir sheets 265a-267a. The Korean Postage Stamp Catalogue (KPSC) gives them the numbers of 188-190 and souvenir sheets 188a-190a.