Sub es()
Dim t(), m As Object, i As Long, Ws As Worksheet
Application.ScreenUpdating = False
Set m = CreateObject("Scripting.Dictionary")
For Each Ws In Sheets(Array("Feuil1", "Feuil2", "Feuil3"))
With Ws
t = .Range("e1", .Cells(Rows.Count, "e").End(xlUp)).Value
For i = 1 To UBound(t)
If Not m.Exists(t(i, 1)) Then m.Add t(i, 1), t(i, 1)
Next i
End With
Next Ws
[f2] = Join(m.Items, " , ")
End Sub