1. An electronic reader comprising: a display; one or more processors; and one or more computer-readable media containing instructions that are executable by the one or more processors to perform actions comprising: receiving, by the electronic reader, an electronic version of a book; receiving, by the electronic reader, a data object separate from content of the electronic version, wherein the data object indicates associations between a plurality of page labels from a print version of the book and a plurality of positions of respective portions of the content within the electronic version; presenting, on the display, a first portion of the content of the electronic version, wherein the first portion of the content corresponds to a first position in the content; determining, from the data object, based at least in part on the first position, a first page label from the print version that is associated with the first position; presenting the first page label concurrently with the first portion of the content on the display; receiving a user selection to highlight a second portion of the content as a highlighted portion of the content, the highlighted portion of the content associated with a second position in the content; generating a textual citation corresponding to the highlighted portion of the content; determining, from the data object, based at least in part on the second position, a second page label to associate with the highlighted portion of the content; and presenting the textual citation associated with highlighted portion of the content, the textual citation including the second page label and bibliographic information.