Analisis perilaku intrahari volatilitas return, volume perdagangan, dan bid-ask spreads saham syariah pada Jakarta Islamic Index Periode 5 September 2011 – 29 Februari 2012 = Analysis of the intraday behaviour of return volatility, trading volume, and bid-ask spread on sharia stocks in Jakarta Islamic Index, Period of 5th September 2011 – 29th February 2012 (Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2012)