They said they bought the books, It's Not About the Bike and EverySecondCounts, because they believed Armstrong's heroic tale of returning to compete drug-free after battling testicular cancer.
The lawsuit, filed this week in federal court in California, also mentions Armstrong's other book, "Every SecondCounts, " and accuses the cyclist and his publishers of fraud and false advertising.
The only way to determine the cause of stroke at present is for the patient to have an MRI or CT scan, both of which can take up valuable time in hospital when everysecondcounts to keep brain damage to a minimum.