When was calligraphy written and how to calculate it?

Calligraphers like to use chronological method. It is to record the year with heavenly stems: A, B, C, D, E, Ji, Ke, Xin, Ren, Gui, Di Zhi, Ugly, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu and Hai. For example, 20 14 is Wu Jianian. The branch chronology can be converted into AD chronology, and the writing time of calligraphy works can be known.