<ref name="ref92vivam">[http://books.google.com/books?id=5LgjunIn1CEC A history of China], Wolfram Eberhard, Plain Label Books, 1967, ISBN 978-1-60303-420-3, ''... Shu Han's difficulty was that its population was not large enough to be able to stand against the northern State of Wei; moreover, it was difficult to carry out an offensive from Shu Han, though the country could defend itself well ...''</ref><ref name="ref08cidep">[http://books.google.com/books?id=2UjzLLOHn_4C The Talent of Shu: Qiao Zhou and the Intellectual World of Early Medieval Sichuan], J. Michael Farmer, SUNY Press, 2008, ISBN 978-0-7914-7164-7, ''... The Fall Of Shu-Han ... The overall state of decline at the court of Liu Shan coupled with a dramatic policy change in Wei placed Shu-Han in a grave situation by 263 CE ...''</ref>