Command Performance : dBASE III by Douglas Hergert

Visual Basic Programming with Windows Applications by Douglas A. Hergert

Your Timex Sinclair 1000 and ZX81 by Douglas Hergert - paperback

Mastering dBASE III : A Structured Approach by Carl Townsend (1985, Trade...

QBasic Programming for Dummies - paperback, 9781568840932, Douglas Hergert

Microsoft QuickBASIC by Douglas Hergert 1987 Microsoft Press Vintage Book

Microsoft QuickBASIC Paperback Douglas Hergert