8Ying C. Stock market prices and volume of sales[J]. Econometrica, 1966, 34: 676-685.
9Clark P K. A subordinated stochastic process model with finite variance for speculative prices[J]. Econometrica, 1973, 41: 135-155.
10Epps T W, Epps M L. The stochastic dependence of security price changes and transaction volumes: Implications for the mixture of distributions hypothesis[J]. Econometrica, 1976, 44: 305-321.