libpng
on SourceForge
libpng16/older-releases/1.6.21beta/libpng-1.6.21beta02.tar.gz
libpng15/older-releases/1.5.26beta/libpng-1.5.26rc01.tar.gz
libpng14/older-releases/1.4.19beta/libpng-1.4.19rc01.tar.gz
libpng12/older-releases/1.2.56beta/libpng-1.2.56rc01.tar.gz