Howarth, S. (1997). A century in oil: The "Shell" Transport and Trading Company 1897-1997. Weidenfeld & Nicolson.
Lua i Stíl Chicago (17ú heag.)Howarth, Stephen. A Century in Oil: The "Shell" Transport and Trading Company 1897-1997. London: Weidenfeld & Nicolson, 1997.
Lua MLA (8ú heag.)Howarth, Stephen. A Century in Oil: The "Shell" Transport and Trading Company 1897-1997. Weidenfeld & Nicolson, 1997.
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