diff --git a/README.md b/README.md
index 2a4a2e0..3244557 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,8 @@
-The .sql is a plain text SQL backup
+The postgresql_book.sql is a plain text SQL backup
 that should be restored with psql.
 
-It consists of the census and staging schemas. As well as some other minor tables
-Some of these are built as part of exercises in the book.  
+It consists of data used in the book
+[PostgreSQL: Up and Running, 4th Edition](https://www.oreilly.com/library/view/postgresql-up-and/9798341660885/ch01.html)
 
 To restore:
 ```sql
@@ -10,3 +10,5 @@ CREATE DATABASE postgresql_book;
 \connect postgresql_book
 \i postgresql_book.sql
 ```
+
+The chapter folders consist of code and data used in the relevant chapters.
\ No newline at end of file