@book{53424,
	author = {Engestrom, Yrjo and Miettinen, R and International Congress for Research on Activity Theory (2nd : 1990 : Lahti, Finland)},
	title = {Perspectives on activity theory},
	publisher = {Cambridge University Press},
	year = {1999},
	series = {Learning in doing},
	address = {Cambridge},
	note = {Bibliography}
}