Clay Spinuzzi William Hart-Davidson Mark Zachry Chains and ecologies: methodological notes toward a communicative-mediational model of technologically mediated writing. 43-50 2006 conf/sigdoc/2006 SIGDOC http://doi.acm.org/10.1145/1166324.1166336 db/conf/sigdoc/sigdoc2006.html#SpinuzziHZ06