The 20th Anniversary of the Chandra X-ray Observatory 2019
2020-2023现在展示： Sierra Leone 2018-Present - （通用）邮票 - 2019 - The 20th Anniversary of the Chandra X-ray Observatory - 4 邮票.
现在展示： Sierra Leone 2018-Present - （通用）邮票 - 2019 - The 20th Anniversary of the Chandra X-ray Observatory - 4 邮票.
![[The 20th Anniversary of the Chandra X-ray Observatory, 类型 ]](https://www.stampworld.com/media/catalogue/Sierra-Leone-2018_Present/Postage-stamps/0894-b.jpg)
