“…Remarks: Even though the form of the function k H (t, s) is known, due to its complicated form, it is not possible to use the methods in Lohvinenko and Ralchenko [12,13,14,15] to study the asymptotic distribution of (α T ,β T ) or the asymptotic marginal distributions ofα T and β T after suitable scaling as T → ∞. However, following ideas in Lohvinenko and Ralchenko [13], we will transform the problem to the study of maximum likelihood estimation for the parameters of sub-fractional Vasicek model to that of estimation of parameters for a subfractional Ornstein-Uhlenbeck process (Mendy [16], Yu [41], Es-Sebaiy-Es-sebaiy [7], Xiao et al [37] ) and derive the asymptotic properties of the corresponding MLE.…”