--- a/doc/interpreter/install.txi	Fri Jul 19 23:37:27 2019 +0200
+++ b/doc/interpreter/install.txi	Sat Jul 20 10:03:31 2019 +0200
@@ -544,9 +544,9 @@
 
 GNU Make, @code{gcc} (and @code{libstdc++}), @code{gnuplot},
 @code{bison}, @code{flex}, and Texinfo are all available from many
-anonymous ftp archives.  The primary site is @url{ftp.gnu.org}, but it
+anonymous ftp archives.  The primary site is @url{ftp://ftp.gnu.org}, but it
 is often very busy.  A list of sites that mirror the software on
-@url{ftp.gnu.org} is available by anonymous ftp from
+@url{ftp://ftp.gnu.org} is available by anonymous ftp from
 @url{ftp://ftp.gnu.org/pub/gnu/GNUinfo/FTP}.
 
 Octave requires approximately 1.4 GB of disk storage to unpack and
@@ -674,7 +674,7 @@
 @item @sc{blas} and @sc{lapack} (@url{http://www.netlib.org/lapack})
 
 Reference versions for both libraries are included in the reference
-@sc{lapack} 3.2.1 distribution from @url{netlib.org}.
+@sc{lapack} 3.2.1 distribution from @url{http://www.netlib.org/}.
 
 @itemize @minus
 @item

--- a/doc/interpreter/preface.txi	Fri Jul 19 23:37:27 2019 +0200
+++ b/doc/interpreter/preface.txi	Sat Jul 20 10:03:31 2019 +0200
@@ -42,7 +42,7 @@
 it for teaching differential equations and linear algebra as well.
 More recently, Octave has been used as the primary computational tool
 for teaching Stanford's online Machine Learning class
-(@url{ml-class.org}) taught by Andrew Ng.  Tens of thousands of students
+(@url{http://ml-class.org}) taught by Andrew Ng.  Tens of thousands of students
 participated in the course.
 
 If you find Octave useful, please let us know.  We are always interested
@@ -135,7 +135,7 @@
 @item
 John A. Turner, Group Leader, Continuum Dynamics @nospell{(CCS-2)},
 @nospell{Los Alamos} National Laboratory, for registering the
-@url{octave.org} domain name.
+@url{https://octave.org} domain name.
 
 @item
 @nospell{James B. Rawlings}, Professor, University of Wisconsin-Madison,