diff --git a/ui/src/routes/works/[wid]/+page.svelte b/ui/src/routes/works/[wid]/+page.svelte
index d79e6bb..9048e5f 100644
--- a/ui/src/routes/works/[wid]/+page.svelte
+++ b/ui/src/routes/works/[wid]/+page.svelte
@@ -16,7 +16,7 @@
  let warn_already_used = false;
  let w = null;
  let gradesP = null;
- let mean = 0;
+ let stats = {"mean": 0, "min": 999, "max": 0};
 
  $: w = data.work;
  $: refresh_submission(data.work);
@@ -34,8 +34,10 @@
          let sum = 0;
          for (const grade of grades) {
              sum += grade.score;
+             if (stats.min > grade.score) stats.min = grade.score;
+             if (stats.max < grade.score) stats.max = grade.score;
          }
-         mean = sum / grades.length;
+         stats.mean = sum / grades.length;
      });
  }
 </script>
@@ -52,8 +54,10 @@
     <SurveyBadge class="ms-2" survey={w} />
 </div>
 
-{#if $user && $user.is_admin && edit}
-    <WorkAdmin work={w} on:saved={() => edit = false} />
+{#if $user && $user.is_admin && (edit || w.endAvailability() < Date.now())}
+    {#if edit}
+        <WorkAdmin work={w} on:saved={() => edit = false} />
+    {/if}
 
     {#if w.description}
         <hr>
@@ -62,7 +66,12 @@
 
     <hr>
     <div class="d-flex justify-content-between align-items-center">
-        <h3 class="mt-3">Notes</h3>
+        <h3 class="mt-3">
+            Notes
+            <small class="text-muted">
+                {#if stats.mean > 0}(moyenne&nbsp;: {Math.round(stats.mean*100)/100}, min&nbsp;: {stats.min}, max&nbsp;: {stats.max}){/if}
+            </small>
+        </h3>
         <button
             class="btn btn-light"
             on:click={() => refresh_grades(w)}
@@ -77,14 +86,13 @@
                 <span>Chargement des notes &hellip;</span>
             </div>
         {:then grades}
+            <p>
+
             <table class="table table-hover table-striped table-sm mb-0">
                 <thead>
                     <tr>
                         <th>Login</th>
-                        <th>
-                            Note
-                            {#if mean > 0}(moyenne&nbsp;: {Math.round(mean*100)/100}){/if}
-                        </th>
+                        <th>Note</th>
                         <th>Commentaire</th>
                         <th>Date de la note</th>
                     </tr>
@@ -115,7 +123,7 @@
                                     <button
                                         class="btn btn-sm btn-danger mx-1"
                                         title="Supprimer la note"
-                                        on:click={() => { grade.delete(); refresh_grades(w); }}
+                                        on:click={() => { grade.delete().then(() => refresh_grades(w)); }}
                                     >
                                         <i class="bi bi-trash"></i>
                                     </button>
diff --git a/works.go b/works.go
index 1ce2e81..e2d857d 100644
--- a/works.go
+++ b/works.go
@@ -472,6 +472,19 @@ func (u *User) GetMyWorkGrade(w *Work) (g WorkGrade, err error) {
 }
 
 func (w *Work) AddGrade(grade WorkGrade) error {
+	u := User{Id: grade.IdUser}
+
+	// Search a previous record
+	g, err := u.GetMyWorkGrade(w)
+	if err != nil && err != sql.ErrNoRows {
+		return err
+	} else if err == nil {
+		_, err = g.Delete()
+		if err != nil {
+			return err
+		}
+	}
+
 	return w.AddGrades([]WorkGrade{grade})
 }