Williams, N. (1965) ‘A language teaching experiment’, Canadian Modern Language Review 22.1: 26-28
http://www.essex.ac.uk/langling/documents/elct/2013/esperanto_tool.pdf
The early research that does exist (e.g. Fisher, 1921; Halloran, 1952, Williams, 1965a, 1965b) is reported in brief terms and thus does not pass today’s quality standards
Also explains why there’s no copy online.
Williams, N. (1965) ‘A language teaching experiment’, Canadian Modern Language Review 22.1: 26-28
http://www.essex.ac.uk/langling/documents/elct/2013/esperanto_tool.pdf
Also explains why there’s no copy online.