Various Scale Dimensions: Scale Dimensions
American Association: nmra.org
European Association: morop.org
Model Railroad on wikipedia: Scale standards
DCC WIKI: dccwiki.com
Model Railroad WIKI : Model Railroad
We supply Hornby / Bachmann/ Liliput/ Roco Train Sets. These are available in Mumbai, Delhi, Hydrabad, Kolkata (India) at more or less the same as international prices. Then why go and purchase from abroad.