diff --git a/extras/readings.md b/extras/readings.md
index 3d387b1..9dffac0 100644
--- a/extras/readings.md
+++ b/extras/readings.md
@@ -7,31 +7,53 @@ some are just great books that you should read at some point in your career.
 Once you have made it through most of the curriculum, knowing whether a book is worth your time will become easier.
 Or, if you are struggling in one of the courses, perhaps reading a book on the subject will help.
 
+## Programming
+
 Name | Author(s)
 :-- | :--:
 [Introduction to Computation and Programming Using Python](https://www.amazon.com/Introduction-Computation-Programming-Using-Python/dp/0262525003/) | John V. Guttag
-[Discrete Mathematics with Applications (4th Edition)](http://www.amazon.com/Discrete-Mathematics-Applications-Susanna-Epp/dp/0495391328/) | Susanna S. Epp
 [How to Design Programs](http://www.ccs.neu.edu/home/matthias/HtDP2e/) | Matthias Felleisen, Robert Bruce Findler, Matthew Flatt, Shriram Krishnamurthi
-[Transaction Processing: Concepts and Techniques](https://www.amazon.com/Transaction-Processing-Concepts-Techniques-Management/dp/1558601902) | Jim Gray, Andreas Reuter
-[Data and Reality: A Timeless Perspective on Perceiving and Managing Information in Our Imprecise World](https://www.amazon.com/Data-Reality-Perspective-Perceiving-Information/dp/1935504215) | William Kent
-[Architecture of a Database System](http://db.cs.berkeley.edu/papers/fntdb07-architecture.pdf) | Joseph M. Hellerstein, Michael Stonebraker, James Hamilton
-[Introduction to Algorithms (3rd Edition)](http://www.amazon.com/Introduction-Algorithms-3rd-MIT-Press/dp/0262033844/) | Thomas H. Cormen,  Charles E. Leiserson, Ronald L. Rivest, Clifford Stein
-[Modern Operating Systems (4th Edition)](http://www.amazon.com/Modern-Operating-Systems-Andrew-Tanenbaum/dp/013359162X/) | Andrew S. Tanenbaum, Herbert Bos
-[Computer Networking: A Top-Down Approach (6th Edition)](https://www.amazon.com/Computer-Networking-A-Top-Down-Approach/dp/1292153598/) | James F Kurose, Keith W Ross
+[Structure and Interpretation of Computer Programs](https://mitpress.mit.edu/sicp/full-text/book/book.html) | Hal Abelson, Jerry Sussman, Julie Sussman 
 [Design Patterns: Elements of Reusable Object-Oriented Software](https://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612) | Erich Gamma, Richard Helm, Ralph Johnson, John Vlissides
 [Refactoring](https://www.refactoring.com/) | Martin Fowler
-[The Architecture of Open Source Applications](http://aosabook.org/en/) | Michael DiBernardo (editor)
-[Compilers: Principles, Techniques, and Tools (2nd Edition)](http://www.amazon.com/Compilers-Principles-Techniques-Tools-2nd/dp/0321486811/) | Alfred V. Aho, Monica S. Lam, Ravi Sethi,  Jeffrey D. Ullman
-[Computer Networks (5th Edition)](http://www.amazon.com/Computer-Networks-5th-Andrew-Tanenbaum/dp/0132126958/) | Andrew S. Tanenbaum, David J. Wetherall
 [Clean Code](https://www.amazon.com/Clean-Code-Handbook-Software-Craftsmanship/dp/0132350882) | Robert Martin
 [Code Complete](https://www.amazon.com/Code-Complete-Practical-Handbook-Construction/dp/0735619670) | Steve McConnell
 [The Pragmatic Programmer](https://www.amazon.com/Pragmatic-Programmer-Journeyman-Master/dp/020161622X) | Andrew Hunt, David Thomas
-[The Mythical Man-Month](https://www.amazon.com/Mythical-Man-Month-Software-Engineering-Anniversary/dp/0201835959/) | Fred Brooks, Jr.
-[Structure and Interpretation of Computer Programs](https://mitpress.mit.edu/sicp/full-text/book/book.html) | Hal Abelson, Jerry Sussman, Julie Sussman 
-[Introduction to Computing: Explorations in Language, Logic, and Machines](http://www.computingbook.org/) | David Evans
-[Applied Discrete Structures](http://faculty.uml.edu/klevasseur/ads2/) | Alan Doerr, Ken Levasseur
+
+## Math
+
+Name | Author(s)
+:-- | :--:
 [Calculus Made Easy](http://www.gutenberg.org/ebooks/33283) | Silvanus P. Thompson 
+[Discrete Mathematics with Applications (4th Edition)](http://www.amazon.com/Discrete-Mathematics-Applications-Susanna-Epp/dp/0495391328/) | Susanna S. Epp
+[Applied Discrete Structures](http://faculty.uml.edu/klevasseur/ads2/) | Alan Doerr, Ken Levasseur
 [Grinstead and Snell’s Introduction to Probability](https://math.dartmouth.edu/~prob/prob/prob.pdf) |Charles M. Grinstead, J. Laurie Snell
-[Compiler Construction](http://www.ethoberon.ethz.ch/WirthPubl/CBEAll.pdf) | Niklaus Wirth 
+
+## Systems
+
+Name | Author(s)
+:-- | :--:
+[Modern Operating Systems (4th Edition)](http://www.amazon.com/Modern-Operating-Systems-Andrew-Tanenbaum/dp/013359162X/) | Andrew S. Tanenbaum, Herbert Bos
+[Computer Networks (5th Edition)](http://www.amazon.com/Computer-Networks-5th-Andrew-Tanenbaum/dp/0132126958/) | Andrew S. Tanenbaum, David J. Wetherall
+[Computer Networking: A Top-Down Approach (6th Edition)](https://www.amazon.com/Computer-Networking-A-Top-Down-Approach/dp/1292153598/) | James F Kurose, Keith W Ross
+
+## Theory
+
+Name | Author(s)
+:-- | :--:
+[Introduction to Computing: Explorations in Language, Logic, and Machines](http://www.computingbook.org/) | David Evans
+[Introduction to Algorithms (3rd Edition)](http://www.amazon.com/Introduction-Algorithms-3rd-MIT-Press/dp/0262033844/) | Thomas H. Cormen,  Charles E. Leiserson, Ronald L. Rivest, Clifford Stein
+
+## Applications
+
+Name | Author(s)
+:-- | :--:
+[Transaction Processing: Concepts and Techniques](https://www.amazon.com/Transaction-Processing-Concepts-Techniques-Management/dp/1558601902) | Jim Gray, Andreas Reuter
+[Data and Reality: A Timeless Perspective on Perceiving and Managing Information in Our Imprecise World](https://www.amazon.com/Data-Reality-Perspective-Perceiving-Information/dp/1935504215) | William Kent
+[Architecture of a Database System](http://db.cs.berkeley.edu/papers/fntdb07-architecture.pdf) | Joseph M. Hellerstein, Michael Stonebraker, James Hamilton
+[The Architecture of Open Source Applications](http://aosabook.org/en/) | Michael DiBernardo (editor)
 [Deep Learning](http://www.deeplearningbook.org/) | Ian Goodfellow, Yoshua Bengio and Aaron Courville
-[Bayesian Reasoning and Machine Learning](http://web4.cs.ucl.ac.uk/staff/D.Barber/pmwiki/pmwiki.php?n=Brml.HomePage) | David Barber
\ No newline at end of file
+[Bayesian Reasoning and Machine Learning](http://web4.cs.ucl.ac.uk/staff/D.Barber/pmwiki/pmwiki.php?n=Brml.HomePage) | David Barber
+[Compilers: Principles, Techniques, and Tools (2nd Edition)](http://www.amazon.com/Compilers-Principles-Techniques-Tools-2nd/dp/0321486811/) | Alfred V. Aho, Monica S. Lam, Ravi Sethi,  Jeffrey D. Ullman
+[Compiler Construction](http://www.ethoberon.ethz.ch/WirthPubl/CBEAll.pdf) | Niklaus Wirth 
+[The Mythical Man-Month](https://www.amazon.com/Mythical-Man-Month-Software-Engineering-Anniversary/dp/0201835959/) | Fred Brooks, Jr.
\ No newline at end of file