When searching with Quick Search, the results will contain records for print and electronic books. You can use the "Books" and "Full-text online" links in the right sidebar to see the online items. You can also search/browse e-book packages directly, which allows you to search all of the e-book content.
E-books are available from a variety of publishers (e.g. Springer, Oxford, Elsevier, Wiley). E-books are also available in aggregate packages, containing books from a variety of publishers. The packages may be multi-disciplinary (e.g. ProQuest Ebook Central) or discipline specific (FOODnetBASE (food science/nutrition)).
For more information and a listing of e-book publishers and packages specific to your discipline, see the e-Book Guide.
E-book packages and publishers: