diff --git a/README.md b/README.md
index de7ca75..f7786f0 100644
--- a/README.md
+++ b/README.md
@@ -55,14 +55,7 @@ cpn("aa", "ab", "abc", "abd") = "a{a,b{,c,d}}"
 cpn("a", "ab", "abc") = "{a{,b{,c}}}"
 ```
 
-*Note:* For the sake of reasoning, strings containing the CPN’s reserved
-characters `{`, `}` and , shall be considered invalid input. In a practical
-implementation, a syntax for „escaping“ these reserved characters should be
-available. For example, in the reference implementation, the `print_trie()`
-function inserts a backslash character `\` in front of every literal `{`, `,`
-and `}`; additionally, every space character ` ` is escaped, because it
-acts as a word separator in GNU Bourne Again Shell and other interpreters
-of brace expansion syntax.
+*Note:* For the sake of reasoning, strings containing the CPN’s reserved characters {, } and , shall be considered invalid input. In a practical implementation, a syntax for „escaping“ these reserved characters should be available. For example, in the reference implementation, the print_trie() function inserts a backslash character \ in front of every literal {, , and }.
 
 ## 2 Implementation
 
@@ -102,3 +95,8 @@ Expected output:
 a ab abc
 ```
 
+## Appendix A: References
+
+* [Initial announcement](https://tk-sls.de/wp/6071)
+* [Update](https://tk-sls.de/wp/6144)
+* [Git repository](https://tk-sls.de/gitlab/tilman/trie)
diff --git a/test/01.sh b/test/01.sh
deleted file mode 100755
index fad4667..0000000
--- a/test/01.sh
+++ /dev/null
@@ -1,26 +0,0 @@
-#!/bin/bash
-
-dir=$(dirname "$(readlink -f "$0")")
-trie="$dir/../trie.py"
-
-read -r -d '' input <<EOF
-a b x
-a b c
-a b c d
-EOF
-
-output=$(echo "$input" | "$trie")
-
-# shellcheck disable=SC2086
-result=$(eval 'for i in '$output' ; do echo "$i" ; done' | sort)
-
-reference=$(echo "$input" | sort | uniq)
-
-if test "$reference" = "$result" ; then
-    rv=0
-else
-    printf 'ERROR: reference=\n%s\nresult=\n%s\n' "$reference" "$result"
-    rv=1
-fi
-
-exit $rv
diff --git a/trie.py b/trie.py
old mode 100755
new mode 100644
index 20bd4ee..6ad1d86
--- a/trie.py
+++ b/trie.py
@@ -34,7 +34,7 @@ def print_trie(trie):
     count = 1
 
     for k in trie:
-        if k == '{' or k == ',' or k == '}' or k == ' ':
+        if k == '{' or k == ',' or k == '}':
             sys.stdout.write('\\')
 
         sys.stdout.write(k)