Sheila Pantry Associates Ltd. (1990). Environment Plus [Đĩa CD-ROM]. USA: Sheila Pantry Associates Ltd.
Chicago Style aipamenaSheila Pantry Associates Ltd. Environment Plus [Đĩa CD-ROM]. USA: Sheila Pantry Associates Ltd, 1990.
MLA aipamenaSheila Pantry Associates Ltd. Environment Plus [Đĩa CD-ROM]. USA: Sheila Pantry Associates Ltd, 1990.
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