GRAY, P. M. (1992). Object - Oriented Data Bases A Semantic Data Model Approach Peter M.d Gray, Krishwarao G. Kulkarni, Norman W. Paton. Prentice - Hall.
Lua i Stíl Chicago (17ú heag.)GRAY, Peter M.D. Object - Oriented Data Bases A Semantic Data Model Approach Peter M.d Gray, Krishwarao G. Kulkarni, Norman W. Paton. Prentice - Hall, 1992.
Lua MLA (8ú heag.)GRAY, Peter M.D. Object - Oriented Data Bases A Semantic Data Model Approach Peter M.d Gray, Krishwarao G. Kulkarni, Norman W. Paton. Prentice - Hall, 1992.
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