Celebratio Mathematica

D. L. Burk­hold­er: “Some ex­tremal prob­lems in mar­tin­gale the­ory and har­mon­ic ana­lys­is,” pp. 99–​115 in Har­mon­ic ana­lys­is and par­tial dif­fer­en­tial equa­tions: Es­says in hon­or of Al­berto P. Calderón (Chica­go, Feb­ru­ary 1996). Edi­ted by M. Christ, C. E. Kenig, and C. Sa­d­osky. Chica­go Lec­tures in Math­em­at­ics. Uni­versity of Chica­go Press, 1999. Es­says in hon­or of Calderón’s 75th birth­day. MR 1743857 Zbl 0954.​60034 incollection