It didn't take long for severe acute respiratory syndrome (SARS) to enter the textbooks. Scientists nabbed the virus responsible for the lethal lung infection only in March 2003, a little more than a month after the disease came to the attention of the international health community, and this free online SARS text is already in its third edition. Edited by infectious-disease specialists Bernd Sebastian Kamps and Christian Hoffmann, it isn't fancy, but it presents plenty of information and includes 10 chapters from five contributors in Hong Kong and Germany. A nice timeline summarizes last year's race to identify the virus and quell the pandemic that began in southern China. Find out what we know about the habits of the SARS coronavirus, which can lurk in animals such as cats and ferrets, and how it spreads (mainly through tiny mucus droplets). Other chapters offer information on diagnosis and prevention and evaluate the many possible treatments doctors have tried, from assisted breathing to interferon. Readers can download versions of the book in six languages.