New Delhi, Sept 05: The Delhi High Court today issued notices to the Liberhan Commission and the Centre on a petition filed by former Uttar Pradesh Chief Minister Kalyan Singh challenging the commission's order summoning him as a witness in the Ayodhya demolition case controversy. Justice A K Sikri directed both the commission and the Centre to file their response to Singh's petition within ten days and posted the matter for further hearing on September 19. Bureau Report