Even though Americans are being warned not to panic over the H1N1 virus (swine flu), and some doctors predict it won’t be much more dangerous than the usual seasonal flus, online book sellers have had an uptick in orders for “The Great Influenza” by John M. Barry.

Barry’s 2004 book is a history of the deadly Spanish-flu pandemic of 1918. The book is now in the top 100 sellers on both amazon.com and barnesandnoble.com

In 2004, reviewer Harry Levins quoted Barry as saying, ”Another pandemic not only can happen. It almost certainly will happen.” The 1918 pandemic actually started in Kansas, Barry said, and killed at least 20 million people around the world.

Every few years, writers offer another book about how the next pandemic may happen. Barry’s apparently leads the pack among the several books about the 1918 virus. Here are some others:

“Flu” by Gina Kolata (1999)

“America’s Forgotten Pandemic” by Alfred W. Crosby (2003)

“A Cruel Wind” by Dorothy Pettit (2008)

There will be a new book about how viruses have evolved along with humans, according news sources. The AP reports that publisher Henry Holt said that it had acquired Nathan Wolfe’s “The Viral Storm.”