Spencer, H. (1900). What is social evolution. In H. Spencer, Various fragments (pp. 197-214). New York, NY, US: D Appleton & Company.
http://dx.doi.org/10.1037/13679-018
The following article, originally published in The nineteenth century for September, 1898, was called forth in reply to one published by Mr. W. H. Mallock in the preceding number of that periodical—one in which, responding at length to a letter of mine in Literature, he had continued that attack on my views he commenced in his Aristocracy and evolution. (PsycINFO Database Record (c) 2016 APA, all rights reserved)