Open. Flip. Sniff. Repeat. That’s a ritual many a bibliophile knows well when cradling an old book. Now, researchers are bringing a sommelier-like appreciation to the art of inhaling a lungful of library smells, Smithsonian.com reports. As paper decomposes, it emits a blend of volatile organic compounds that our noses recognize as the familiar old book smell. In a study published last week in the journal Heritage Science, researchers developed a preliminary “historic paper odor wheel” that lists organic molecules associated with categories of scents like earthy, woody, and smoky, similar to aroma wheels for coffee and wine. Measuring and understanding these compounds present in museums and libraries could aid in preservation of their collections, and might even lead to recreation of historic smells for bookworms everywhere to enjoy.