Robert Obojski Books

Coin Collector s Price Guide

By Robert Obojski

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Coin collector s price guide

By Robert Obojski

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The most practical guide covering all regular-issue coins of both the United States and Canada, from the first U.S. release in 1776 to the 2000 coins commemorating the millennium of Leif Ericson's...

Baseball s Strangest Moments

By Robert Obojski

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Baseball Memorabilia

By Robert Obojski

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Out Of Left Field Baseball Trivia

By Robert Obojski

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Stamp collectors' handbook

By Fred Reinfeld

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Poland in pictures

By Robert Obojski

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Baseball's strangest moments

By Robert Obojski

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True stories of events on and off the baseball field highlighting some unusual or unique aspects about players, executives, rules, and customs.

Baseball's strangest moments

By Robert Obojski

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True stories of events on and off the baseball field highlighting some unusual or unique aspects about players, executives, rules, and customs.

Benjamin franklin postage stamp Stamp collector's price guide

By Robert Obojski

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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.