Citation means that when quoting other people's data, the source of the data must be indicated, including the author's name, title or periodical name, page number, publishing unit, year, month and day, etc. Or you should list references. Then list the names of the authors of the references ... and so on. There must be at least four references. To quote other people's original words, you should enclose them with "……" and mark 1 or 2, 1 or 2 at the end of the original words as the serial number of your listed references.