@inbook{Emerson1972a,
author = {Emerson, R.M.},
title= {Exchange theory, part I: A psychological basis for social exchange},
year = {1972a},
editor = {Berger, J.},
editor = {Zelditch, M.},
editor = {Anderson, B.},
booktitle = {Sociological theories in progress, Vol. 2},
address = {Boston},
publisher = {Houghton Mifflin},
pages = {38--57},
}