1. R. E. Paley, “Some theorems on orthogonal functions,” Stud. Math., No. 3, 226–238 (1931).
2. E. M. Stein, “Interpolation of linear operators,” Trans. Amer. Math. Soc., 83, No. 21, 482–492 (1956).
3. V. I. Kolyada, “On some generalizations of the Hardy-Littlewood-Paley theorem,” Mat. Zametki, 51, Issue 3, 24–34 (1993).
4. S. G. Krein, Yu. I. Petunin, and E. M. Semenov, Interpolation of Linear Operators [in Russian] Nauka, Moscow 1978.
5. S. Bennet and R. Sharpley, “Weak-type inequalities for H p and BMO” Proc. Symp. Pure Math., 35, No. 1, 201–229 (1979).