This is the 6282nd most frequent Russian word.
умных
"Smart" or "intelligent" (plural or genitive case).
Here, 'умных' is the plural genitive case of 'умный', agreeing with 'учеников' and attributing the quality of 'smart' to the 'students'.
В школе есть специальный клуб для умных учеников.
There is a special club for smart students at school.
In this sentence, 'умных' is the plural genitive case of 'умный', applied to 'авторов' to denote authors with intelligence.
Друзья всегда выбирают интересные книги от умных авторов.
Friends always choose interesting books by smart authors.
The word 'умных' serves as the plural genitive case of 'умный', describing 'ученых' as intelligent or possessing notable intellect.