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http://books.google.com/books?id=oFlcAgAAQBAJ&pg=PA308&lpg=PA308&dq=charcoal+yang+wan+li&source=bl&ots=tXfDr0l42R&sig=pxwOtAOTh-z5pdSATtLccxIvJhY&hl=en&sa=X&ei=nlFPU9SEJpC2yAT9xoKQDg&ved=0CCgQ6AEwAA#v=onepage&q=charcoal&f=false