How much are Guan Linying's calligraphy and calligraphy works? How to identify them? What's the value?

National first-class artists and Chinese paintings have participated in many art exhibitions organized by China Artists Association. Judge of the 8th National Art Exhibition. His works have been exhibited and collected in Japan, Singapore, the former Soviet Union, Hongkong, Taiwan Province and other countries and regions. The value of this work is about 300,000 pounds per square foot. Specific and introductory.