National Academies Press E-books This link opens in a new windowContains more than 4,000 titles in PDF format. All of the PDFs can be downloaded for free by the chapter or the entire book. here are a small number of reports that never had PDF files and therefore, those reports are not available for download. In addition, part of the series, "Nutrient Requirements of Domestic Animals" are not be available in PDF and future titles in this series will also not have PDFs associated with them.