diff --git a/share/man/man3/pthread_condattr.3 b/share/man/man3/pthread_condattr.3
index f11b50070d3..f3b1d363982 100644
--- a/share/man/man3/pthread_condattr.3
+++ b/share/man/man3/pthread_condattr.3
@@ -24,7 +24,7 @@
 .\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 .\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 .\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-.Dd May 31, 2016
+.Dd October 27, 2023
 .Dt PTHREAD_CONDATTR 3
 .Os
 .Sh NAME
@@ -112,6 +112,10 @@ threads in the same process as the one that created the object.
 The condition variable it is attached to may be accessed by
 threads in processes other than the one that created the object.
 .El
+See
+.Xr libthr 3
+for details of the implementation of shared condition variables,
+and their limitations.
 .Sh RETURN VALUES
 If successful, these functions return 0.
 Otherwise, an error number is returned to indicate the error.
@@ -153,6 +157,7 @@ The value specified in
 is not one of the allowed values.
 .El
 .Sh SEE ALSO
+.Xr libthr 3 ,
 .Xr pthread_cond_init 3 ,
 .Xr pthread_cond_timedwait 3
 .Sh STANDARDS
diff --git a/share/man/man3/pthread_mutexattr.3 b/share/man/man3/pthread_mutexattr.3
index 30537b9a9f8..8f4d0d9a06a 100644
--- a/share/man/man3/pthread_mutexattr.3
+++ b/share/man/man3/pthread_mutexattr.3
@@ -29,7 +29,7 @@
 .\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 .\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 .\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-.Dd October 1, 2021
+.Dd October 27, 2023
 .Dt PTHREAD_MUTEXATTR 3
 .Os
 .Sh NAME
@@ -150,6 +150,10 @@ threads in processes other than the one that created the object,
 assuming other processes share access to the memory where the mutex
 was allocated.
 .El
+See
+.Xr libthr 3
+for details of the implementation of the shared mutexes,
+and their limitations.
 .Pp
 The
 .Fn pthread_mutexattr_setrobust
@@ -334,6 +338,7 @@ Invalid value for
 .Fa attr .
 .El
 .Sh SEE ALSO
+.Xr libthr 3 ,
 .Xr pthread_mutex_init 3
 .Sh STANDARDS
 The