Grumbler, that firsthand information. A firsthand account is a story as told by a witness.

Я знаю, но в русском это самый близкий перевод. И о истории можно сказать "информация".
https://context.reverso.net/перевод/английский-русский/first-hand+account

It’s FIRSTHAND, no hyphen. The English in that example from Reverso is not the best. If you search for it without the hyphen, you get different results.

https://www.google.com/search?q=%22%D1%80%D0%B0%D1%81%D1%81%D0%BA%D0%B0%D0%B7+%D0%B8%D0%B7+%D0%BF%D0%B5%D1%80%D0%B2%D1%8B%D1%85+%D1%80%D1%83%D0%BA%22&sxsrf=APwXEdeNTWgdGGVdUhOgvILhKQUUY02sLw:1681215359161&source=lnms&tbm=bks&sa=X&ved=2ahUKEwio8Jei56H-AhVCRzABHWCJBH0Q0pQJegQIBRAI&biw=1867&bih=1060&dpr=2

OK, you add it.

Спасибо Вам