E-books zu QBasic und QuickBasic im PDF-Format contains PDF copies of the GW-BASIC Manual and PC Magazine's BASIC Techniques and Utilities Book.

GW-BASIC LANGUAGE
The Encyclopedia of Computer Languages - BASIC(ID:176/bas009)
TinyBasic

http://www.atariarchives.org/
http://www.atariarchives.org/basicgames/
http://www.atariarchives.org/morebasicgames/
http://www.atariarchives.org/bigcomputergames/

Vintage BASIC is open source software, provided under the BSD license.
Vintage Basic - Games

ScriptBasic

BASICODE

Overview of BASICODE-3
Seopedia - BASICODE

GitHub - jacgoudsmit/Basicode old archive with source files for Basicode support for DOS on the IBM PC compatibles. Public Domain.

Arithmetic Operators
Order of precedence:

^       Exponentiation
-       Negation
*       Multiplication
/       Floating-point Division
+       Addition
-       Substraction