Chu, Yeong-Jin; Liu, Tseng-Hong (1965), "On the Shortest Arborescence of a Directed Graph", Scientia Sinica: Chung-kuo k`o hsueh, XIV (10): 1396–1400
Chu, Yeong-Jin; Liu, Tseng-Hong (1965), "On the Shortest Arborescence of a Directed Graph", Scientia Sinica: Chung-kuo k`o hsueh, XIV (10): 1396–1400