Gaya APA
Duffy, T. (1988).
Four software tools with lotus1-2-3, word perfect, and dBase III plus .
Belmont, California:
Wadsworth Publishing Company.
Gaya MLA
Duffy, Tim.
"Four software tools with lotus1-2-3, word perfect, and dBase III plus".
Belmont, California:
Wadsworth Publishing Company,
1988.
Text.