Valuing an antique book for resale can be a complex process that requires knowledge and research. Here are some steps you can follow to help determine the value of an antique book:

1. Research: Start by conducting thorough research about the book and its author. Look for information on the book's publication date, edition, publisher, and any notable characteristics or historical significance. This research will help you establish a foundation for assessing its value.

2. Condition assessment: Evaluate the condition of the book. Factors such as the presence of dust jackets, tears, stains, foxing (brown spots caused by aging), missing pages, or repairs can significantly affect its value. Take note of any damages or restorations done to the book.

3. Edition and printing: Determine the edition and printing of the book. First editions are generally more valuable than later editions. Look for indications of the edition on the copyright page or title page. Check for any statements such as "First Edition", Xth Impression or Xth Printing or a number line indicating the printing.

4. Rarity: Consider the rarity of the book. Books that are difficult to find or are in limited supply tend to have higher values. Look for information on the print run or the number of copies published. If it is a limited or special edition, that can also add to its desirability.

5. Demand and market trends: Research the current demand for the specific book and the general market trends for antique books. Check online marketplaces, auction results, and specialized booksellers to gauge the level of interest and the prices similar books are selling for. Look for any recent news or events that may have influenced the book's demand or popularity.

6. Appraisals and expert opinions: Consider seeking professional appraisals or consulting experts in the field of antiquarian books. They can provide valuable insights and expertise based on their knowledge and experience. Their assessments can help you establish a fair value for the book.

7. Condition reports and photographs: Document the condition of the book thoroughly, both in writing and with clear photographs. This information will be useful when selling the book and can help potential buyers assess its condition accurately.

8. Comparative analysis: Compare the book you're valuing to similar books that have been sold or are currently available for sale. Look for books with similar editions, conditions, and characteristics. Pay attention to the prices at which these books have been sold to determine a reasonable price range.

9. Adjustments: Make any necessary adjustments to the value based on factors such as condition, rarity, and demand. For instance, if the book is in exceptionally good condition or has unique features, it may warrant a higher valuation. On the other hand, significant damages or a lack of demand may lower the value.

10. Consider the market: Keep in mind that the value of antique books can fluctuate based on market conditions, trends, and collector preferences. The value you determine should be based on the current market, but it's essential to understand that the market can change over time.

Valuing antique books is a specialized skill, and it may be worth consulting professionals in the field to ensure accuracy.

Just because a book is old or rare doesn’t mean it is valuable.