Connected Papers: A visual tool that helps speed up your literature search
Struggling to search research papers by inputting keywords or topics in the traditional databases or Google for your literature review? In this blog, we introduce Connected Papers, a visual tool to help speed up literature searches and explore academic papers.
About Connected Papers
Connected Papers is a handy and powerful tool. It simplifies the process of searching for research papers, fastens the literature discovery, and makes literature exploration more visual, interactive and straightforward.
How Does Connected Papers Work?
Connected Papers lists the following operations  on its website.
- To create each graph, Connected Papers analyzes an order of ~50,000 papers and selects a few dozen with the strongest connections to the origin paper.
- In the graph, papers are arranged according to their similarity. That means that even papers that do not directly cite each other can be strongly connected and very closely positioned. Connected Papers is not a citation tree.
- Their similarity metric is based on the concepts of Co-citation and Bibliographic Coupling. According to this measure, two papers that have highly overlapping citations and references are presumed to have a higher chance of treating a related subject matter.
- Their algorithm builds a Force Directed Graph to distribute the papers in a way that visually clusters similar papers together and pushes less similar papers away from each other. Upon node selection, they highlight the shortest path from each node to the origin paper in similarity space.
- Their database is connected to the Semantic Scholar Paper Corpus (licensed under ODC-BY). The team has done the job of compiling hundreds of millions of published papers across many scientific fields.
Searching with a “Seed Paper” in Connected Papers
The exploration of the connected papers in a visual graph starts with a “seed” paper (relevant paper). You can search the title of the seed paper or enter the keyword or topic to the search box, Connected Papers will list the related papers in the drop-down menu. Or you can input the DOI to search for the seed paper and Connected Papers will list the matched seed paper for you. For example, the paper “A familial cluster of pneumonia associated with the 2019 novel coronavirus indicating person-to-person transmission: a study of a family cluster” by Dr. Chan, Jasper Fuk Woo and others (2020) (DOI: 10.1016/S0140-6736(20)30154-9) is used as the seed paper.
After inputting the paper identifier in the search box, click “Build a graph” to generate the visual graph.
Connected Papers generates graphs that consist of relevant papers that are similar to the seed/origin paper. The left panel shows the seed/origin papers and their relevant papers, and the right panel displays the detailed information of the selected paper on the left panel or selected node in the middle panel.
In the middle panel, it visualizes the seed paper and its similar papers. Seed paper is marked with a purple circle on the graph. The node and line on the graph have the following meanings.
- Each node represents a related paper
- Color of the node: Color represents the publication year; darker nodes are more recent works; lighter nodes are earlier works
- Size of the node: Size represents the citation of the paper; bigger nodes are highly cited papers and verse versa
- Clusters of the node: The cluster represents the similarity of the papers; the closer the clusters mean the papers are high in similarity and verse versa
Line and proximity: they show the similarity of the papers; similar papers are close together and with connecting lines.
Some features of Connected Papers are given below.
Discovering the relevant prior and derivative works
The Prior Works button is used for discovering previous seminal works in the field of their interest  . The Prior Works List can be sorted by title, first/last author, year, number of citations, and graph citations.
Click the Derivative Works button to detect the surveys (literature reviews) of the field or the recent relevant works that follow the input paper  . The Derivative Works List can be sorted by title, first/last author, year, number of citations, and graph references.
Adding additional origin: Multi-origin graphs
Connected Papers has recently unveiled a new feature, “Multi-origin graphs” . The new “Add origin” button on the right-side panel is for selecting any node on the graph and adding it as a second origin. For example, we select the paper, “Temporal profiles of viral load in posterior oropharyngeal saliva samples and serum antibody responses during infection by SARS-CoV-2: an observational cohort study” by To, Kelvin Kai-Wang et al in The Lancet Infectious Diseases 20.5 (2020).
After adding the additional origin, Connected Papers will construct a new graph where all the nodes/papers in it are selected by similarity to both the origin papers. To remove the origin, select the origin paper and click “Remove origin”.
Exporting the Connected Paper List
Users can export reference lists to the reference managers, for instance, Zotero, EndNote, and Mendeley. Click the “Expand” button to find the detailed paper list. Users can sort the list by title, authors, year, number of citations and references, and percentage of similarity to the original paper, Click the “Download” button to export the bibliography list.
Starting 1 August 2022, Connected Papers launch a new business model. It has two types of accounts: Free and Premium. The Free plan will include all the features in Connected Papers but will be limited to 5 graphs per month.
Other Literature Mapping Tools
There are several literature mapping tools  available presently. In this blog, we are going to give a brief introduction to two other popular literature mapping tools, Inciteful and Litmaps for your information. A comparison of these two tools and Connected Papers is shown in the below table.
|Complexity||• Simple tool|
• Use one seed paper and create multi-origin graph(s)
|• Customizable tool|
• Use multiple seed papers in the iterative process 
|• More complex tool|
• Use multiple seed papers and overlapping maps, combining search with citation relationships and visualization 
|Memberships||Free, Academic & Business||Free||Free, Litmaps Pro, & Team License|
We are going to explore more about Inciteful and Litmaps in our coming blogs. Stay tuned with our Researcher Connect.
In addition to the keyword search and using the citation links in the traditional databases and Google, Connected Papers provides an alternative method for literature search.
Connected Papers makes literature discovery easier, saves the time and effort of the researchers and accelerates their research. It is especially helpful to novices or young scholars/students when they carry out their literature review at the beginning of their research . They can start with the seed references, use Connected Papers to fill in the gaps, and find the other relevant references.
1. Connected Papers. Connected Papers: How does it work? 2022. Available from: https://www.connectedpapers.com/about
2. Connected Papers. Connected Papers: Explore connected papers in a visual graph 2022. Available from: https://www.connectedpapers.com/
3. Tay A. 3 new tools to try for Literature mapping – Connected Papers, Inciteful and Litmaps: Medium; 2022 [updated 2022-08-01]. Available from: https://aarontay.medium.com/3-new-tools-to-try-for-literature-mapping-connected-papers-inciteful-and-litmaps-a399f27622a
4. Connected Papers. Announcing Premium accounts, multi-origin graphs and more: Connected Papers; 2022 [updated 2022-07-27]. Available from: https://medium.com/connectedpapers/announcing-premium-accounts-multi-origin-graphs-and-more-92e8dbd66848
5. Tay A. List of Innovative Literature mapping tools 2022. Available from: http://musingsaboutlibrarianship.blogspot.com/p/list-of-innovative-literature-mapping.html
6. ScienceEditor. Connected Papers: A Game-Changing Tool for Researchers: ServiceScape; 2020. Available from: https://www.servicescape.com/blog/connected-papers-a-game-changing-tool-for-researchers