What are Yan Zhenqing's calligraphy copying stickers?

Yan Bei in front of the pagoda is his work after the age of 60, which is the highest peak of calligraphy. He wants to write a manuscript for his nephew, and the manuscript is written by him for his nephew, which is called "the second post in the world". However, compared with Preface to Lanting, his calligraphy attainments are even worse!