8Allen B. , 1990," Information as an economic commodity", American Economic Review 80 (2) :268 -273.
9Allen B. , 1993,“ Stock markets and resource allocation”,In Capital markets and financial intermediation. C. Mayer and X. Vives(eds). Cambridge: Cambridge University Press.
10Barton O. ,Kim. , Lim S. & Stevens D. ,1998,"Using analysts' forecasts to measure properties of analysts' information environment" ,The Accounting Review 73( 4 ) :421 -433.