ISBN 13-978-07603-3673-1* الموقع الرسمي لكاتربيلر* Antique Caterpillar Machinery Owners Club* Antique Caterpillar Machinery Enthusiasts* Photos of early Holt machinery* Caterpillar Tractor Company Photograph Collection at Baker Library Historical Collections, Harvard Business School
ISBN 978-0-7603-3673-1==External links==* Caterpillar Inc. Official Website* Cat Products Official Website* Caterpillar Rental Website* Caterpillar Inc SEC Filings* Antique Caterpillar Machinery Owners Club* Antique Caterpillar Machinery Enthusiasts* Photos of early Holt machinery* Caterpillar Tractor Company Photograph Collection at Baker Library Historical Collections, Harvard Business School