COBOL

COBOL Programming Fundamental

COBOL Programming Standards

A J Marston

Enterprise COBOL for z/OS documentation library

GNU COBOL Programmers Guide

Gary L. Cutler

ILE COBOL Programmer's Guide

Micro Focus: OO Programming with Object COBOL for UNIX (1999)

MERANT International Ltd.

OpenCOBOL 1.1 - Programmer's Guide

Visual COBOL: A Developer's Guide to Modern COBOL

Paul Kelly

Programmeren in COBOL

Wikibooks