Fun fact: opera can be used as an effective form of self defense. Being trained to resonate clearly throughout a packed opera hall without amplificatuon enables you to produce very
We're talking "tiny woman who happens to be a trained soprano bursting the ear drums of a would-be attacker with nothing but a high note" loud!
It’s a piano practice book from China called 拜厄钢琴基本教程 (Beyer Piano Basic tutorial). I don’t know much about piano, so I think this is a book on piano lessons about Ferdinand Beyer? Something like that