แหล่งที่มา WikiPedia: เจสตอร์ http://www.alexa.com/siteinfo/jstor.org http://chronicle.com/article/The-Hard-Numbers-Behi... //doi.org/10.1108%2F01604950210434551 //doi.org/10.1108%2F02641610810878549 //doi.org/10.1108%2F10650750610640801 //doi.org/10.1300%2FJ111v46n02_05 //doi.org/10.2307%2F455826 http://www.ithaka.org/about-ithaka http://jstor.org http://about.jstor.org/download/file/fid/1423
