The 4-Percent Universe: Dark Matter, Dark Energy, and the Race to Discover the Rest of Reality

Most of the items in our store are used. The item's condition grade is indicated near the bottom of the product description. If you have any questions regarding specific details of an item, please contact us. We use the following rating scale:

Books:

• Used - Very Good: Item may have minor cosmetic defects (marks, wears, cuts, bends, crushes) on the cover, spine, pages or dust cover. Shrink wrap, dust covers, or boxed set case may be missing. Item may contain remainder marks on outside edges, which should be noted in listing comments. Item may be missing bundled media. 
• Used - Good: All pages and cover are intact (including the dust cover, if applicable). Spine may show signs of wear. Pages may include limited notes and highlighting. Gently used ex-library books with library stickers and markings may be classified as good. Shrink wrap, dust covers, or boxed set case may be missing. Item may be missing bundled media. 
• Used - Acceptable: All pages and the cover are intact, but shrink wrap, dust covers, or boxed set case may be missing. Pages may include limited notes, highlighting, or minor water damage but the text is readable. Item may but the dust cover may be missing. Pages may include limited notes and highlighting, but the text cannot be obscured or unreadable.

CDs/DVDs/Discs:

• Used - Good: Case may be damaged or come repackaged. Disc may have up to 1.5cm marking but is in great working condition. 
• Used - Acceptable: A product with extensive external signs of wear, but is in great working condition. The case may be damaged. The cover art, liner, notes, or other inclusion may be marked, or one or all of these items may be missing.

Shipping: Most orders are shipped within 2 business days.

Returns: We want you to be completely satisfied with your purchase. If you're not, you can return your order within 30 days of purchase for a refund.