You can purchase POLYMATH-NETWORK from these places
Go to Kucoin.com
The People's Exchange
Go to Bittrex
Bittrex is one of the larger crypto to crypto exchanges offering a large number of trading pairs into bitcoin - including all the major cryptos such as darkcoin, nextcoin and litecoin
Go to Huobi
Huobi (火币网) is a Chinese digital currency trading platform and exchange based in Beijing. Huobi was founded in September 2013.