Man pages matching name mbstowcs in section 3:

mbstowcs.3.en	debian 10 / manpages-dev
mbstowcs.3.es	debian 10 / manpages-es
mbstowcs.3.ja	debian 10 / manpages-ja-dev
mbstowcs.3.pt	debian 10 / manpages-pt-dev
mbstowcs.3.en	debian 11 / manpages-dev
mbstowcs.3.fr	debian 11 / manpages-fr-dev
mbstowcs.3.ja	debian 11 / manpages-ja-dev
mbstowcs.3.pt	debian 11 / manpages-pt-dev
mbstowcs.3.en	debian 12 / manpages-dev
mbstowcs.3.ja	debian 12 / manpages-ja-dev
mbstowcs.3.pt_BR	debian 12 / manpages-pt-br-dev