http://www.geocities.ws/ralf_schreyer/ward/download/pure_sociology.pdf
https://archive.org/details/jstor-2761775
https://archive.org/details/jstor-2761666
https://archive.org/details/jstor-2761636
https://archive.org/details/jstor-2761755
https://archive.org/details/jstor-2761651
https://archive.org/details/jstor-2761826
https://archive.org/details/jstor-2761775
https://archive.org/details/jstor-2761666
https://archive.org/details/jstor-2761636
https://archive.org/details/jstor-2761755
https://archive.org/details/jstor-2761651
https://archive.org/details/jstor-2761826