13. The method of claim 7 , wherein determining the second similarity relationship comprises determining the second similarity relationship between the text cluster and the determined text subgroups positioned backward of the text cluster, wherein linking comprises linking the text cluster to the backward-positioned determined text subgroup having the highest second similarity relationship.
7. A method comprising: determining text subgroups within an electronic text; determining a relevance score for each word of one or more words within the determined text subgroups, the relevance score based on one of a frequency of occurrence of the word within one of the determined text subgroups and a type of the word within one of the determined text subgroups; selecting, by an electronic device, a text subgroup from the determined text subgroups that corresponds to a current user position within the electronic text; selecting, by the electronic device, a text seed within the selected text subgroup based on the relevance scores of the words within the selected text subgroup; determining a first similarity relationship between the selected text seed and one or more of the determined text subgroups adjacent to the selected text subgroup that do not include the selected text seed; creating a text cluster by associating the text seed with the one or more adjacent determined text subgroups based on the first similarity relationship; and for each of the determined text subgroups outside of the text cluster: determining an activity indication of time when a user has read the determined text subgroup; determining a second similarity relationship between content of the determined text subgroup and the text cluster; and linking the determined text subgroup to the text cluster based on the second similarity relationship and on the determined time the user read the text subgroup.