db/conf/pos/VelezDDFHMR90.html Fernando Vélez Vineeta Darnis David J. DeWitt Philippe Futtersack Gilbert Harrus David Maier Michel Raoux Implementing the O<sub>2</sub> Object Manager: Some Lessons. 131-138 1990 conf/pos/90 POS db/conf/pos/pos90.html#VelezDDFHMR90 POS/1990/P131.pdf