Li Yingzhen (1431-1493), Calligraphy in Running Script. Photo: Sotheby's. 

signed Yingzhen (3), with two collectors' seals, qian (3),ceng wei zhi yu zhi shan zhai suo you; ink on paper, album leaves; 22.5 by 26.7 cm. 8 7/8  by 10 1/2  in. (and various sizes). Estimation 15,000 -- 25,000 USD

Litterature: Calligraphy of Ming and Qing Masters, Vol. 1, Jiang Zhaoshen, Tokyo: Nigensha, 1987, pp. 6, 7, 19-25 

Sotheby's. Fine Classical Chinese Paintings & Calligraphy. New York | 19 sept. 2013 - http://www.sothebys.com