Books that provide a comprehensive understanding of ETPU (Electronic Transfer Pricing Units) machines include:

1. "The Electronic Taxing Machine: How ETPUs Are Changing the Face of Accounting and Finance" by Andrew H. McLean This book provides an indepth analysis of how ETPUs work and their impact on accounting practices.

2. "EPTRP: The Electronic Taxpayer Responsibility Program" by David A. Cline A practical guide to using ETPUs effectively, covering topics such as compliance and best practices.

3. "Taxation and ETPU Systems: International Practice and Policy Considerations" edited by Michael P. O'Donnell and James L. Smith A collection of essays from leading experts in the field, this book offers a broad perspective on the use of ETPUs worldwide.

4. "The Electronic Taxing System: A Guide for Practitioners" by Richard D. Spero An introduction to the electronic tax system, providing stepbystep instructions and practical guidance for tax professionals.

These books not only equip readers with the knowledge necessary to understand and utilize ETPU systems but also offer insights into the legal, technical, and ethical implications of their implementation. They serve as essential resources for anyone interested in learning more about this innovative approach to taxation and financial management.