It's so hard to look for English documents/books about China's Southern Northern Dynasties Era, especially those about Northern Wei (To-pa Wei) and Liu Sung. Ti`m hoa`i kho^ng ra ddu+o+.c gi`, o+? LOC, Duke, UNC, Emory dde^`u o co'; va` hi`nh nhu+ "Cambridge History of China" thi` chu+a xua^'t ba?n volume 2. Co' ba'c na`o co' tips chi kho^ng ? Thank you in advance