What works are there about the art of singing in traditional Chinese opera?

The center of China traditional opera art is the actor's stage art, therefore, the first work about singing art appeared in drama theory. The Singing Theory of Yan Nan Zhi An (134 1 Yuan Yuan) is the earliest vocal music work in China. This paper summarizes the previous singing experience, the requirements for voice and articulation, artistic expression, the basic emotional characteristics of the Seventeen Gongdiao, the local characteristics of music, aesthetic requirements and the evaluation of singers. All of them are involved and have many opinions, which provided important vocal music materials for the study of vocal music art in Song and Yuan Dynasties. The Rhyme of the Central Plains by Zhou Deqing (1277 ~ 1365, Tingzhai, Gao 'an, Jiangxi) is a rhyme book based on the rhymes of Yuan Qu works and the northern languages. It is divided into 19 rhyme, and the flat words are divided into two categories: Yin Ping and Yangping, and the vocal words are given flat words respectively. This is the earliest rhyme book of Beiqu, and it is also the basis of the development of rhyme in Ming and Qing Dynasties. The book "Examples of Orthodoxy" lists 335 kinds of Qupai in Yuan Dynasty, and makes a study on their pronunciation identification, word usage and freeze-frame of Quci. In the section of "Ten Methods of Writing Ci", he discussed ten aspects that should be paid attention to in writing Ci, such as knowing rhyme, creating words, using things, using words, titles, duality and sentence endings. In view of the creative situation at that time, he put forward the idea that "writing Yuefu can't hurt the melody", emphasizing the important position of melody in composition, and also put forward that "before making his words, make his intentions first, make his intentions first." Hu Zuotong (1227 ~ 1293, Shao Kai, Zishan, Wu 'an, Cizhou, now a native of Cixian, Hebei) put forward the theory of "nine beauties" in actor performance, from the quality and accomplishment of actors to the experience and performance of characters, as well as stage art and theater. Xia Tingzhi's Collection of Brothels (Zi Bohe,No. Xuegun, born at the end of Yuan Dynasty and the beginning of Ming Dynasty) describes the artistic life of more than 0/00 actors in several big cities in Yuan Dynasty, which provides a lot of historical materials for the study of actors in Yuan zaju.