Analysis of information sources in references of the Wikipedia article "Shuyang County" in English language version.
For example, many Mandarin dialects have more than four tones. Hangzhou has no fewer than seven, such that it was previously classified as a Wu dialect ( Simmons 1992; Baxter 2000, 106–8). In the Jiang-Huai region five-tone dialects are not uncommon, with six-tone ones reported on the Northern/Central boundary (Norman 1988, 194). These represent a retention of one of the original four tones of Middle Chinese (the rù tone), as distinguished from the more common Mandarin trait of having lost this tone while collapsing the two-way register distinction between the three others into a four-tone contrast not contingent upon register
