Fair use refers to the non-commercial use of published works by others under the circumstances expressly stipulated by the law, without the permission of the copyright owner and without payment to them. The circumstances expressly stipulated by the law mainly include: (1) Personal study, research or appreciation, using the published works of others; (2) Free performance of published works; (3) Copying, painting, photography, and video recording of art works installed or displayed in outdoor public places; (4) Translate published works created in Chinese language into minority languages for publication and distribution.
 Ding Wei wrote the paper and copied Geng's papers published in a certain journal for reference is fair use according to the above regulations.