Man pages matching name usleep in section 1:

usleep.1.zh_CN	debian 10 / manpages-zh
usleep.1.zh_TW	debian 10 / manpages-zh
usleep.1.zh_CN	debian 11 / manpages-zh
usleep.1.zh_TW	debian 11 / manpages-zh
usleep.1.zh_CN	debian 12 / manpages-zh
usleep.1.zh_TW	debian 12 / manpages-zh