1. A computer implemented method comprising: accessing a digital document, wherein the digital document relates to one or more topics; generating a list of expert students, wherein the expert students have authored one or more annotations relating to a topic similar to the one or more topics in the digital document by: extracting similar documents from a database of digital documents; filtering the similar documents into a set of documents that one or more users have annotated; computing a confidence score for each annotation imported by a user; and computing a local user rank of each expert student based on the confidence score; ordering the list of expert students according to the local user rank, wherein the local user rank identifies a level of expertise of the expert students; and presenting the ordered list of expert students, where the ordered list comprises a pre-defined number of expert students with a level of expertise meeting a predefined threshold.