R. Fletcher and S. Leyffer, Nonlinear programming without a penalty function, Math. Program., 91 no. 2 (2002) 239–269.
 A. Bose and K. Mukherjee, Estimating the arch parameters by solving linear equations, J. Time Ser. Anal., 24 no. 2 (2003) 127–136.
 E. Parzen, On spectral analysis with missing observations and amplitude modulation, Sankhyā Ser. A, 25 (1963) 383–392.
 N. Shephard, Statistical aspect of ARCH and stochastic volatility, In D. R. Cox, D. V. Hinkley, O. E. Barndorff-Nielsen (Eds.), Time series models in econometrics, finance and other fields, London: Chapman and Hall, 1996.
 A. A. Weiss, Asymptotic theory for ARCH models: Estimation and testing, Econometric Theory, 2 no. 1 (1986) 107–131.