Papers are excerpted or quoted. Although some are qualitative value expressions of the paper, they do not always show the quality of the paper, and some may be used to oppose critical excerpts from the thesis. Other quotes may only be ideological and coherent. The abstracts journals do not pay attention to it, do not cite or omit, and the papers that are not cited are not necessarily unimportant and not excellent. From this we can infer:. ['Most articles in abstracts are of low quality.', 'Some high-quality papers will not appear in abstracts.', 'Really good papers are not cited.', 'The most controversial papers are most likely to be cited.']