John Koehler Books

A commentary on Galatians

By John Philipp Koehler

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Benjamin The Road to Capernaum

By John Koehler

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Tsaoism

By Dr. Thomas Tsao, John Koehler

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Case of the Russian Maids

By Timothy Choquette, John Koehler, John Leonard Koehler

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Spies in the Vatican

By John O. Koehler

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Evaluates the Soviet Union's espionage campaign against the Catholic Church, drawing on previously unseen documents to reveal an assassination order against Pope John Paul II and a Russian spy netw...

Works of Art

By John Koehler

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How to Convert ISBN-10 to ISBN-13 (and Vice Versa): A Complete Guide

If you’re in the world of books—whether as a publisher, librarian, bookseller, or avid collector—you’ve likely come across the terms ISBN-10 and ISBN-13. Understanding these formats and knowing how to convert between them is essential for maintaining consistency and compatibility in book records. In this post, we’ll cover everything you need to know about ISBN conversions, step by step.

What is an EAN and How Does it Relate to an ISBN?

If you’ve ever purchased a product online or in a store, you’ve likely come across a barcode. Behind these barcodes lies a standardized system that makes modern commerce possible. Two key codes often encountered are the EAN (European Article Number) and ISBN (International Standard Book Number). But what are they, how are they connected, and why are they so crucial? Let’s explore.