5. A method comprising: presenting, by a computing device, on a display, a first portion of content of an electronic version of a content item; determining a first position in the electronic version with which the first portion of content is associated; receiving a data object that indicates associations between page labels from a print version of the content item and positions of respective portions of content in the electronic version; 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 content; receiving a selection of a second portion of content of the electronic version as a selected portion; generating a textual citation corresponding to the selected portion; determining, from the data object, based at least in part on a second position associated with the selected portion, a second page label associated with the selected portion; and presenting the textual citation associated with selected portion, the textual citation including the second page label.
5. A method comprising: presenting, by a computing device, on a display, a first portion of content of an electronic version of a content item; determining a first position in the electronic version with which the first portion of content is associated; receiving a data object that indicates associations between page labels from a print version of the content item and positions of respective portions of content in the electronic version; 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 content; receiving a selection of a second portion of content of the electronic version as a selected portion; generating a textual citation corresponding to the selected portion; determining, from the data object, based at least in part on a second position associated with the selected portion, a second page label associated with the selected portion; and presenting the textual citation associated with selected portion, the textual citation including the second page label. 8. The method as recited in claim 5 , wherein the data object includes at least two different types of page labels, wherein: a first type of page label of the at least two different types of page labels corresponds to a first range of pages in the print version; a second type of page label of the at least two different types of page labels corresponds to a second range of pages in the print version; a plurality of the page labels of the first type are associated in the data object with a first plurality of positions; and a plurality of the page labels of the second type are associated in the data object with a second plurality of positions.