diff --git a/README.md b/README.md
index d8193a7..7a87bbf 100644
--- a/README.md
+++ b/README.md
@@ -4,11 +4,11 @@ EPUB Content containing accessibility tests for reading systems
 
 ## Index of materials
 
-* `content/epub30-test-0301/`: Basic Functionality
+* `content/epub30-test-0301/`: Basic Functionality (ISBN 9781003410126)
 * `content/epub30-test-0302/`: Non-Visual Reading (ISBN 9781003410119) 
-* `content/epub30-test-0303/`: Visual Adjustments
-* `content/epub30-test-0304/`: Read Aloud
-* `content/epub30-test-0320/`: Media Overlays 
+* `content/epub30-test-0303/`: Visual Adjustments (ISBN 9781003410133)
+* `content/epub30-test-0304/`: Read Aloud (ISBN 9781003410140)
+* `content/epub30-test-0320/`: Media Overlays (ISBN 9781003410157)
 * `content/epub30-test-0330/`: Math (longer book, not on site)
 * `content/epub30-test-0340/`: Extended Descriptions (longer book, not on site)
 * `content/epub30-test-0350/`: Extended Descriptions (basic)
diff --git a/content/epub30-test-0301/EPUB/package.opf b/content/epub30-test-0301/EPUB/package.opf
index 090433f..dd54e17 100644
--- a/content/epub30-test-0301/EPUB/package.opf
+++ b/content/epub30-test-0301/EPUB/package.opf
@@ -2,6 +2,8 @@
 <package xmlns="http://www.idpf.org/2007/opf" version="3.0" unique-identifier="uid">
   <metadata xmlns:dc="http://purl.org/dc/elements/1.1/">
     <dc:identifier id="uid">com.github.epub-testsuite.epub30-test-0301</dc:identifier>
+    <dc:identifier id="isbn-id">9781003410126</dc:identifier>
+    <meta refines="#isbn-id" property="identifier-type" scheme="onix:codelist5">15</meta>
     <dc:description>These tests include starting the reading system and opening the titles, navigating the content, searching, and using bookmarks and notes.</dc:description>
     <dc:title>Fundamental Accessibility Tests: Basic Functionality</dc:title>
     <!-- repeat creator element for all contributors -->
diff --git a/content/epub30-test-0303/EPUB/package.opf b/content/epub30-test-0303/EPUB/package.opf
index 648625e..b77eb16 100644
--- a/content/epub30-test-0303/EPUB/package.opf
+++ b/content/epub30-test-0303/EPUB/package.opf
@@ -2,6 +2,8 @@
 <package xmlns="http://www.idpf.org/2007/opf" version="3.0" xml:lang="en" unique-identifier="uid">
   <metadata xmlns:dc="http://purl.org/dc/elements/1.1/">
     <dc:identifier id="uid">com.github.epub-testsuite.epub30-test-0303</dc:identifier>
+    <dc:identifier id="isbn-id">9781003410133</dc:identifier>
+    <meta refines="#isbn-id" property="identifier-type" scheme="onix:codelist5">15</meta>
     <dc:title>Fundamental Accessibility Tests: Visual Adjustments</dc:title>
     <dc:description>These tests include changing the font and text size, colors, brightness, compatibility with magnification utilities and support for high contrast and SVG images.</dc:description>
     <!-- repeat creator element for all contributors -->
diff --git a/content/epub30-test-0304/EPUB/package.opf b/content/epub30-test-0304/EPUB/package.opf
index c89a2fb..0c2ad6f 100644
--- a/content/epub30-test-0304/EPUB/package.opf
+++ b/content/epub30-test-0304/EPUB/package.opf
@@ -2,6 +2,8 @@
 <package xmlns="http://www.idpf.org/2007/opf" version="3.0" unique-identifier="uid" xml:lang="en">
   <metadata xmlns:dc="http://purl.org/dc/elements/1.1/">
     <dc:identifier id="uid">com.github.epub-testsuite.epub30-test-0304</dc:identifier>
+    <dc:identifier id="isbn-id">9781003410140</dc:identifier>
+    <meta refines="#isbn-id" property="identifier-type" scheme="onix:codelist5">15</meta>
     <dc:title>Fundamental Accessibility Tests: Read Aloud</dc:title>
     <dc:description>These tests include start, pause and resume Read Aloud, reading order, punctuation support and visual emphasis of the spoken text.</dc:description>
     <!-- repeat creator element for all contributors -->
diff --git a/content/epub30-test-0320/EPUB/package.opf b/content/epub30-test-0320/EPUB/package.opf
index ec3ddc0..1eb6745 100644
--- a/content/epub30-test-0320/EPUB/package.opf
+++ b/content/epub30-test-0320/EPUB/package.opf
@@ -1,6 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
 <package version="3.0" xmlns:dc="http://purl.org/dc/elements/1.1/" unique-identifier="uid" xmlns="http://www.idpf.org/2007/opf">
 	<metadata>
+	<dc:identifier id="isbn-id">9781003410157</dc:identifier>
+    <meta refines="#isbn-id" property="identifier-type" scheme="onix:codelist5">15</meta>
 		<meta property="dcterms:license">https://creativecommons.org/licenses/by/4.0/</meta>
 		<meta property="role" refines="#creator1" scheme="marc:relators">aut</meta>
 		<meta property="file-as" refines="#creator1">Consortium, DAISY</meta>