 A collection of his letters is held at the National Library of Medicine in Bethesda, Maryland.In 1664 Redi wrote his first monumental work "Osservazioni intorno alle vipere" ("Observations on vipers") to his friend Lorenzo Magalotti, secretary of the "Accademia del Cimento".In this he began to break the prevailing scientific myths (which he called "unmasking of the untruths") such as vipers drink wine and shatter glasses, their venom is poisonous if swallowed, the head of dead viper is an antidote, the viper's venom is produced from the gallbladder, and so on.