* holidays.el: Update reference to the papers in S-P&E.

        (filter-visible-calendar-holidays): Test for nil date.

3 files changed, 12 insertions, 11 deletions

diff --git a/lisp/calendar/cal-french.el b/lisp/calendar/cal-french.el
index 84e0de91e5b..2f9c92e9345 100644
--- a/lisp/calendar/cal-french.el
+++ b/lisp/calendar/cal-french.el
@@ -28,11 +28,11 @@
 ;; This collection of functions implements the features of calendar.el and
 ;; diary.el that deal with the French Revolutionary calendar.
 
-;; Technical details of the French Revolutionary calendrical calculations can
-;; be found in ``Calendrical Calculations, Part II: Three Historical
-;; Calendars'' by E. M. Reingold,  N. Dershowitz, and S. M. Clamen,
-;; Report Number UIUCDCS-R-92-1743, Department of Computer Science,
-;; University of Illinois, April, 1992.
+;; Technical details of the Mayan calendrical calculations can be found in
+;; ``Calendrical Calculations, Part II: Three Historical Calendars''
+;; by E. M. Reingold,  N. Dershowitz, and S. M. Clamen,
+;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993),
+;; pages 383-404.
 
 ;; Comments, corrections, and improvements should be sent to
 ;;  Edward M. Reingold               Department of Computer Science
diff --git a/lisp/calendar/cal-mayan.el b/lisp/calendar/cal-mayan.el
index f0d5b7981f3..9d88e4e60fa 100644
--- a/lisp/calendar/cal-mayan.el
+++ b/lisp/calendar/cal-mayan.el
@@ -46,8 +46,8 @@
 ;; Technical details of the Mayan calendrical calculations can be found in
 ;; ``Calendrical Calculations, Part II: Three Historical Calendars''
 ;; by E. M. Reingold,  N. Dershowitz, and S. M. Clamen,
-;; Report Number UIUCDCS-R-92-1743, Department of Computer Science,
-;; University of Illinois, April, 1992.
+;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993),
+;; pages 383-404.
 
 ;;; Code:
 
diff --git a/lisp/calendar/holidays.el b/lisp/calendar/holidays.el
index 5dd4a537cf1..00d96531a64 100644
--- a/lisp/calendar/holidays.el
+++ b/lisp/calendar/holidays.el
@@ -38,8 +38,8 @@
 ;; Software--Practice and Experience, Volume 20, Number 9 (September, 1990),
 ;; pages 899-928.  ``Calendrical Calculations, Part II: Three Historical
 ;; Calendars'' by E. M. Reingold,  N. Dershowitz, and S. M. Clamen,
-;; Report Number UIUCDCS-R-92-1743, Department of Computer Science,
-;; University of Illinois, April, 1992.
+;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993),
+;; pages 383-404.
 
 ;; Hard copies of these two papers can be obtained by sending email to
 ;; reingold@cs.uiuc.edu with the SUBJECT "send-paper-cal" (no quotes) and
@@ -662,8 +662,9 @@ in the calendar window."
   (let ((visible)
         (p l))
     (while p
-      (if (calendar-date-is-visible-p (car (car p)))
-          (setq visible (append (list (car p)) visible)))
+      (and (car (car p))
+           (calendar-date-is-visible-p (car (car p)))
+           (setq visible (append (list (car p)) visible)))
       (setq p (cdr p)))
     visible))