Analysis of information sources in references of the Wikipedia article "Sông Đồ Môn" in Vietnamese language version.
[...] adding that winter is the optimal time of year for North Koreans who wish to defect to cross the frozen Tumen River that separates the country from China, if security is not too heavy.
[...] adding that winter is the optimal time of year for North Koreans who wish to defect to cross the frozen Tumen River that separates the country from China, if security is not too heavy.
