PageHeader : Funkcialaj Ekvacioj, 24 (1981), 331-344 Title : Some Remarks on Second Order Abstract Cauchy Problems(*) AuthorInfo : By AuthorInfo : H. O. FATTORINI AuthorInfo : (University of California, U.S.A.) section : 1. Introduction. section : 2. The space $E_{1}$ . section : 3. The principal value square root reduction. section : 4. Other square root reductions. section : 5. Hille's results on higher order equations. section : 6. Conclusions. section : References