1. A system for providing visual suggestions for document classification via injection, comprising: a database to store clusters of unclassified documents and a set of reference documents, each reference document associated with a classification code; and a server comprising a central processing unit, memory, an input port to receive the clusters from the database, and an output port, wherein the central processing unit is configured to: compare one or more of the unclassified documents within one such cluster to the reference documents; identify for the cluster, one or more of the reference documents that are similar to the compared unclassified documents; inject the similar reference documents into the cluster; set a threshold for a number of the similar reference documents to be injected into the cluster; and display each of the similar reference documents in the cluster with a visual indicator representative of the associated classification code, display the unclassified documents of the cluster, and provide a suggestion for classification for one of the unclassified documents within each cluster based on the visual indicators of the similar reference documents.