Spence, R. (1993). Rick Spence's Clipper 5.2 power programmer's guide. Sybex.
Lua i Stíl Chicago (17ú heag.)Spence, Rick. Rick Spence's Clipper 5.2 Power Programmer's Guide. San Francisco: Sybex, 1993.
Lua MLA (8ú heag.)Spence, Rick. Rick Spence's Clipper 5.2 Power Programmer's Guide. Sybex, 1993.
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