From 1fc877324507b2ab9c434909230be03af0892db4 Mon Sep 17 00:00:00 2001
From: Daniel Kochmanski <daniel@turtleware.eu>
Date: Fri, 28 Apr 2017 22:18:37 +0200
Subject: [PATCH] doc: add some information

---
 src/doc/new-doc/standards/hashtables.txi | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/doc/new-doc/standards/hashtables.txi b/src/doc/new-doc/standards/hashtables.txi
index 78aa5e790..ecf497ef4 100644
--- a/src/doc/new-doc/standards/hashtables.txi
+++ b/src/doc/new-doc/standards/hashtables.txi
@@ -15,6 +15,11 @@ keyword argument to @t{cl:make-hash-table} with the desired kind of
 weakness value (@t{NIL} means that the hash table has only strong
 references).
 
+For more information see
+@url{https://www.haible.de/bruno/papers/cs/weak/WeakDatastructures-writeup.html,Weak
+References - Data Types and Implementation} by Bruno Haible.
+
+@lspindex hash-table-weakness
 @deffn {ext} {hash-table-weakness} ht
 Returns type of the hash table weakness. Possible return values are:
 @t{:key}, @t{:value}, @t{:key-and-value}, @t{:key-or-value} or @t{NIL}.