If it were not for their adversaries, little or nothing would be known about the exact content of Kuskova's and Prokopovich's criticism of orthodox Marxism. At the time they expressed their views orally or in letters, only one of which was intended for publication. (This, incidentally, explains to a large degree the lapses in style as well as some of the inconsistencies in their writings of this period.) Four of their critical writings have survived in print. They are:

(a) a private letter from Kuskova to Akselrod, apparently written in the second half of March or beginning of April 1898, and published by Plekhanov in Vademecum, pp. 17–21. The authorship and approximate date can be established on the basis of the following information:

authorship–according to Plekhanov the letter was written by M.M. This was Kuskova's pseudonym at the time, and she herself stated explicitly in her early memoirs that she wrote the letter. Hence, despite the fact that the grammatical composition indicates a male author, it was apparently written by Kuskova and not Prokopovich;

the date–according to Plekhanov it was written in spring 1898. On the basis of the available evidence it is possible to be more precise and state that it was written between the middle of March and the beginning of April. It could not have been written before 13 March (see above p. 81n.) nor after 5 April, since between 6 and 26 April Kuskova was in Zurich.