This guidance relates to Cite Them Right Harvard style.
The 1978 ebook is available to University of Worcester staff and students. It isn't a usual edited book whereby the chapters are written by different people, rather it is Vygotsky's earlier work, translated and republished with additional material from those editors. In fact some people have given the question a lot of thought! There is no 100% correct answer on this one - the main thing is to make sure your reference is traceable by the reader.
In Harvard style, one suggestion for in-text citation might be:
Vygotsky (Cole et al, 1978) states.....
However Vygotsky (Cole et al, 1978) also claimed that.....
A suggested reference for your reference list:
Cole, M. et al. (eds.) (1978) L.S. Vygotsky: Mind in society: the development of higher psychological processes. London: Harvard University Press.