de_dust06
cs_assaultvilla_v3
cs_xmas
cs_office_extended
css_galleria
de_sidewalk
de_abbaye_premium

  To play them you need to download them from...
  cstrike-planet.com   or   fpsbanana.com

Put them into your map folder ... usually located in -
C:\Program Files\Valve\Steam\steamapps\yourname\counter-strike source\cstrike