 |  | Nigerian National Petroleum Corporation, Jan- Dec 2001 |
| | Nigerian National Petroleum Corporation, Jul 2002 |
| | Nigerian National Petroleum Corporation, Mar 2001 |
| | Nigerian National Petroleum Corporation, Jan- Dec 2000 |
| | Nigerian National Petroleum Corporation, Apr 2002 |
| | Freight & Commodity International. Vol.1, No.1, Sep-Oct, 1998 |
| | Nigerian National Petroleum Corporation, Jan- Mar 2000 |
| | Nigerian National Petroleum Corporation, Jan- Dec 1999 |
| | Nigerian National Petroleum Corporation, Jan- Dec 2002 |
| | Nigerian National Petroleum Corporation, Feb 2002 |
| | Nigerian National Petroleum Corporation, Aug 2002 |
| | Nigerian National Petroleum Corporation, Mar 2002 |
| | Nigerian National Petroleum Corporation, Jan 2001 |
