Choosing one, or mixing them all
#
###################################################################################
#Versão Codinome   Status                                                         #
#  15 	 Duke 	   Codinome anunciado                                             #
#  14 	 Forky 	   "teste (testing)" — sem data de lançamento definida            #
#  13 	 Trixie    Versão "estável (stable)" atual                                #
#  12 	 Bookworm  Versão "antiga (oldstable)" atual                              #
#  11 	 Bullseye  Versão "muito antiga (oldoldstable)" atual, sob o suporte LTS  #
#  10 	 Buster    Versão arquivada, sob suporte LTS estendido pago por terceiros #
#   9 	 Stretch   Versão arquivada, sob suporte LTS estendido pago por terceiros #
###################################################################################
#
One little known feature of apt-get, aptitude and all related tools is that it is relatively easy to mix and match packages from any release.

First, you have to configure your /etc/apt/sources.list correctly. Mine looks like this:

deb ftp://my.debian.mirror.org/debian/packages stable         main contrib non-free
deb ftp://my.debian.mirror.org/debian/security stable/updates main contrib non-free
deb ftp://my.debian.mirror.org/debian/packages testing         main contrib non-free
deb ftp://my.debian.mirror.org/debian/security testing/updates main contrib non-free
deb ftp://my.debian.mirror.org/debian/packages unstable         main contrib non-free

deb ftp://ftp.at.debian.org/debian/ testing main contrib non-free
deb ftp://ftp.at.debian.org/debian/ stable main contrib non-free
deb ftp://ftp.at.debian.org/debian/ unstable main contrib non-free
deb ftp://ftp.at.debian.org/debian/ experimental main contrib non-free

deb-src ftp://ftp.at.debian.org/debian/ testing main contrib non-free
deb-src ftp://ftp.at.debian.org/debian/ stable main contrib non-free
deb-src ftp://ftp.at.debian.org/debian/ unstable main contrib non-free
deb-src ftp://ftp.at.debian.org/debian/ experimental main contrib non-free

deb http://security.debian.org/ testing/updates main
deb http://security.debian.org/ stable/updates main

###################################################################################
#Versão Codinome   Status                                                         #
#  15 	 Duke 	   Codinome anunciado                                             #
#  14 	 Forky 	   teste (testing) — sem data de lançamento definida              #
#  13 	 Trixie    Versão estável (stable) atual                                  #
#  12 	 Bookworm  Versão antiga (oldstable) atual                                #
#  11 	 Bullseye  Versão muito antiga (oldoldstable) atual, sob o suporte LTS    #
#  10 	 Buster    Versão arquivada, sob suporte LTS estendido pago por terceiros #
#   9 	 Stretch   Versão arquivada, sob suporte LTS estendido pago por terceiros #
################################################################################### 
#
# See http://wiki.debian.org/DebianReleases
#
deb http://deb.debian.org/debian/ stable main contrib non-free non-free-firmware
deb-src http://deb.debian.org/debian/ stable main contrib non-free non-free-firmware
#
deb http://deb.debian.org/debian-security stable-security main contrib non-free non-free-firmware
deb-src http://deb.debian.org/debian-security stable-security main contrib non-free non-free-firmware
#
deb http://deb.debian.org/debian stable-backports main contrib non-free non-free-firmware
#
##################
# Brasil Mirrors #
##################
#ftp.br.debian.org
#debian.c3sl.ufpr.br
#debian.pop-sc.rnp.br
#mirror.blue3.com.br
#mirrors.ic.unicamp.br
#mirror.uepg.br
#mirror.ufscar.br
#############################
# apt install netselect-apt #
#############################