>>> bb/172835@156749
>>> bb/172839@156749
But I'm going to throw one at a time to make it clear how simple and difficult it is at the same time.
https://ya.ru/search/?text=Chemical+pure+substances.+Yu.+V.+Karyakin+I.+I.+Angelov
Chemically pure. Y. V. Karjakin, I. I. Angelov.
p 375 - phosphorus tribromide, p 378 - phosphorus trichloride