No changes in text of librettos.

译本文字未改动。

youdao

All four librettos reprinted with a different typeface (which I feel is more readable) for stage directions.

四个译本分别采用不同的字体刊登（我认为这样会更具可读性）。

youdao

Source material: Primary source for all four librettos is Schott's 1899 vocal scores (republished in the United States by Schirmer in 1904).

资料来源：四个版本都来源于1899年schott出版的歌谱(该歌谱1904年在美国由Schirmer再版)。

youdao

Mr. Argento writes his own librettos, and his predominantly tonal music makes text intelligibility paramount while maintaining its own distinctive profile.

WSJ: A Liebestod to Die For | Tristan und Isolde | Houston Grand Opera | By Heidi Waleson

The city's Heritage Museum has a hall devoted to artefacts related to the art and its history, including a reconstructed theatre, librettos and multimedia programs.

BBC: Cantonese opera returns to Hong Kong

Peking opera is sung and recited using primarily Beijing dialect, and its librettos are composed according to a strict set of rules that prize form and rhyme.

UNESCO: Intangible Cultural Heritage