--- a/doc/AMR-study-utils	Fri May 10 18:20:06 2024 +0000
+++ b/doc/AMR-study-utils	Fri May 10 18:45:36 2024 +0000
@@ -1,3 +1,14 @@
+Historical article from 2023-04
+===============================
+
+The following article was written in 2023-04, a year before the introduction of
+libtwamr.  All of the utilities described in this article, plus even older
+gsm-amr2efr and gsm-efr2amr utilities described in AMR-EFR-conversion article,
+are implemented in amrconv subdirectory of the present source package, and are
+entirely independent of libtwamr - they predate this library.
+
+Original article follows; the utilities described therein are still useful:
+
 As of this writing (2023-04), the main emphasis here at Themyscira Wireless is
 on classic FR and EFR codecs, particularly the latter, rather than AMR.
 However, given the close relation between GSM EFR and the highest MR122 mode of