From c9c3a79fdb0ceff767c98b60c3a1218be0ceb482 Mon Sep 17 00:00:00 2001
From: Margaret Hu <70117942+margaret-hu@users.noreply.github.com>
Date: Sat, 5 Oct 2024 18:07:56 -0700
Subject: [PATCH] Update free-programming-books-subjects.md (#11378)

Adding a PDF that introduces the world of logic, sets, and relations using Z notation.
---
 books/free-programming-books-subjects.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/books/free-programming-books-subjects.md b/books/free-programming-books-subjects.md
index 9f19bc2d7..440f0f1ac 100644
--- a/books/free-programming-books-subjects.md
+++ b/books/free-programming-books-subjects.md
@@ -660,6 +660,7 @@ Books that cover a specific programming language can be found in the [BY PROGRAM
 * [Small Memory Software](https://smallmemory.charlesweir.com/book.html) - Charles Weir, James Noble (HTML)
 * [Software Technical Writing: A Guidebook](https://jamesg.blog/book.pdf) - James Gallagher (PDF)
 * [The Web Development Glossary](https://github.com/frontenddogma/web-development-glossary) – Jens Oliver Meiert
+* [Using Z Specification, Refinement, and Proof](http://www.usingz.com/usingz.pdf) -  Jim Woodcock, Jim Davies (PDF)
 * [Web Almanac](https://almanac.httparchive.org/static/pdfs/web_almanac_2019_en.pdf) (PDF)
 * [Writing Native Mobile Apps in a Functional Language Succinctly](https://www.syncfusion.com/ebooks/writing_native_mobile_apps_in_a_functional_language_succinctly) - Vassili Kaplan