Update free-programming-books-subjects.md (#10351)

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books/free-programming-books-subjects.md

@@ -221,6 +221,7 @@ Books that cover a specific programming language can be found in the [BY PROGRAM
 
 * [A Data-Centric Introduction to Computing](https://dcic-world.org) - Kathi Fisler, Shriram Krishnamurthi, Benjamin S. Lerner, Joe Gibbs Politz (HTML)
 * [Computational Thinking](https://www.cs.cmu.edu/~15110-s13/Wing06-ct.pdf) - Jeannette Wing, Carnegie-Mellon University (PDF)
+* [Computer Science Class XI](https://cbseacademic.nic.in/web_material/doc/cs/1_Computer-Science-Python-Book-Class-XI.pdf) - CBSE (PDF)
 * [Computer Science I](https://cse.unl.edu/~cbourke/ComputerScienceOne.pdf) - Chris Bourke (PDF)
 * [Computer Science II](https://cse.unl.edu/~cbourke/ComputerScienceTwo.pdf) - Chris Bourke (PDF)
 * [CS Principles: Big Ideas in Programming](https://www.openbookproject.net/books/StudentCSP/) - Mark Guzdial, Barbara Ericson (HTML)