1. A method comprising: under control of one or more computing systems configured with specific executable instructions: receiving a content item associated with a content source, the content item including one or more approved portions that have been approved by a publisher for providing as a search result; identifying the one or more approved portions of an electronic book; extracting the one or more approved portions from the content item received from the content source to form extracted textual content; creating a digital sample for the content item, wherein the digital sample includes the extracted textual content from the content item, a type associated with the content item and a content item identifier that identifies the content item; receiving a search query from a client computing device; searching for the search query within the digital sample; identifying search results within the digital sample associated with the search query based at least in part on the searching; mapping the search results to a portion of the content item received from the content source, wherein the mapping the search results to the portion of the content item comprises: receiving a results identifier associated with the search results, and an associated text string; mapping the results identifier to the content item identifier; determining a location of the associated text string from within the content item based at least in part on the results identifier; and converting the associated text string to a format for presentation on the client computing device; and providing the portion of the content items to the client computing device.