Lev Vygotsky Readings in the Goucher Library for Bibliographic Annotations
Because Vygotsky figures so prominently in the assumptions of late Twentieth-Century composition researchers, you might be interested in reading some chapters by and about his work. Although he was working more in the "Old Paradigm" of research, reasoning from general experience rather than as the result of direct observation and experiment, his reasoning and conclusions have proved extremely influential and thought-provoking.
Works by Vygotsky:
Works about Vygotsky's ideas and influence on education: