13. A computing device comprising: a display; one or more processors; and one or more computer-readable media including instructions that, when executed by the one or more processors, program the one or more processors to: present, on the display, a first portion of content of an electronic version of a content item; receive, via a user interface, a first page label associated with a print version of the content item; determine, based at least in part on a data object, a first position in the content associated with the first page label, wherein the data object indicates associations between page labels from the print version and positions of respective portions of content in the electronic version; present, on the display, a second portion of content of the electronic version corresponding to the first position; receive a selection of a third portion of content of the electronic version as a selected portion; generate a textual citation corresponding to the selected portion; determine, 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 present the textual citation associated with selected portion, the textual citation including the second page label.
13. A computing device comprising: a display; one or more processors; and one or more computer-readable media including instructions that, when executed by the one or more processors, program the one or more processors to: present, on the display, a first portion of content of an electronic version of a content item; receive, via a user interface, a first page label associated with a print version of the content item; determine, based at least in part on a data object, a first position in the content associated with the first page label, wherein the data object indicates associations between page labels from the print version and positions of respective portions of content in the electronic version; present, on the display, a second portion of content of the electronic version corresponding to the first position; receive a selection of a third portion of content of the electronic version as a selected portion; generate a textual citation corresponding to the selected portion; determine, 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 present the textual citation associated with selected portion, the textual citation including the second page label. 18. The computing device as recited in claim 13 , wherein the data object includes at least two different types of page labels from the print version, wherein a first type of the page labels of the at least two different types of page labels comprises Arabic numerals, and a second type of the page labels of the at least two different types of page labels comprises symbols different from Arabic numerals.