Here are 4 covers franked with stamps on this theme sent by fellow blogger, Zhou Fan. Thank you very much!
As you can see, 2 of the covers bear the same stamps devoted to the Reform and Opening-up Policy in China (改革开放). I am sure the identicals were sent out mistakenly by Zhou Fan. And this is what I am missing.
In addition, a gorgeous souvenir sheet titled "Homeland in My Heart (祖国在我心中)" completes this set. It is also interesting to note that these covers are actually Cécogramme, meaning a letter or a package containing documents sent or received by visually impaired people or by assisting organizations. Two types of documents are accepted in such mail; embossed documents (e.g. texts written in the Braille alphabet) and sound documents such as audio books. Cécogramme can be identified by the word Cécogramme printed on the cover and also by a special label.