Command Performance : dBASE III by Douglas Hergert

1985 Microsoft Press by Douglas Hergert dBase III Command Performance Series

Visual Basic Programming with Windows Applications by Douglas A. Hergert

Your Timex Sinclair 1000 and ZX81 by Douglas Hergert - paperback

QBasic Programming for Dummies - paperback, 9781568840932, Douglas Hergert

QBASIC Programming for Dummies by Hergert, Douglas A.

Microsoft QuickBASIC by Douglas Hergert 1987 Microsoft Press Vintage Book

How to Use Microsoft Windows 95 3rd Edition By Douglas Hergert. ISBN 1562765655