Map of Szczecin tram system 2013
Own work
(Original text : http://sharemap.org/public/Trams_in_Szczecin
Geospatial data sources: 

Open Street Map Data (ODbL) - http://www.openstreetmap.org/copyright
NORTAD - http://www.bts.gov/publications/north_american_transportation_atlas_data/
Natural Earth - http://www.naturalearthdata.com/)
Szczecinolog