diff --git a/docs/04-api-design/references.adoc b/docs/04-api-design/references.adoc
index cf1affe..37266d9 100644
--- a/docs/04-api-design/references.adoc
+++ b/docs/04-api-design/references.adoc
@@ -1,6 +1,6 @@
 === {references}
 
-<<geewax>>, <<zimmermann>>, <<lauret>>, <<amundsen>>, <<higginbotham>>
+<<geewax>>, <<zimmermann>>, <<lauret>>, <<amundsen>>, <<higginbotham>>, <<json>>, <<http-problem>>
 
 // tag::DE[]
 // silence asciidoctor warnings
diff --git a/docs/99-references/00-references.adoc b/docs/99-references/00-references.adoc
index bd34c30..75e2a47 100644
--- a/docs/99-references/00-references.adoc
+++ b/docs/99-references/00-references.adoc
@@ -23,6 +23,12 @@ This section contains references that are cited in the curriculum.
 
 - [[[higginbotham,Higginbotham 2021]]] James Higginbotham, "Principles of Web API Design: Delivering Value with APIs and Microservices", Addison-Wesley, 2021
 
+- [[[http-problem,HTTP Problem Details]]] Mark Nottingham, Erik Wilde, and Sanjay Dalal, "Problem Details for HTTP APIs", Internet Proposed Standard RFC 9457, July 2023
+
+**J**
+
+- [[[json,JSON]]] Tim Bray, "The JavaScript Object Notation (JSON) Data Interchange Format", Internet Standard RFC 8259, December 2017
+
 **L**
 
 - [[[lauret,Lauret 2019]]] Arnaud Lauret, "The Design of Web APIs", Manning Publications, 2019