Is Zhang Xiumin's 1979 calligraphy valuable?

Worth some money. Zhang Xiumin, male, born in June, 1937, originally from Gan County, Shaanxi Province, is the president of Beijing Runbaozhai Painting and Calligraphy Institute in China. His calligraphy is very valuable. Zhang Xiumin used to be the vice president of Shaanxi Art Institute, a famous calligrapher in China, and the general adviser of calligraphy and painting friendship in the preparatory office of China Pavilion, the patriotic education base of China Patriotic Engineering Federation.