db/journals/jacm/HullY84.html Richard Hull Chee-Keng Yap The Format Model: A Theory of database Organization. 518-544 1984 31 J. ACM 3 http://doi.acm.org/10.1145/828.832 db/journals/jacm/jacm31.html#HullY84 JACM/31/P0518.pdf