Prompt γ-γ-γ and x-γ-γ coincidence studies following the spontaneous fission of ²⁵²Cf were carried out first at Oak Ridge then at Gammasphere first with 36 and later with 72 Ge and two x-ray detectors and a long x-ray-γ coincidence experiment at Idaho. Many new cases of correlated pairs in cold (zero neutron emission) binary fission are observed and for the first time the heavier correlated pairs are identified in ternary fission where the third partners are α, ⁶He (or α2n), ¹⁰Be and, tentatively, ¹⁴C. Theoretical calculations were carried out of the relative yields of cold binary and ternary fission. There is reasonable agreement between the relative theoretical and experimental yields. New level structures and isotopes include new octupole deformations, identical bands and other structures. Stable octupole deformation is now observed in N=86, ¹⁴⁰Xe, ¹⁴²Ba and ¹⁴⁴Ba and ¹⁴³Ba, ¹⁴⁸Ba and to higher spin in ¹⁴⁴Ba. The ^142–146Ba data provide the first evidence for the predicted disappearance of stable octupole deformation at high spins from band crossings. Identical yrast bands are observed with widely different neutron and proton numbers in ^98,100Sr, ^108,110Ru, ^112,116Pd, ^144,146Ba, ^152,154,156Nd, ¹⁵⁶Sm, ¹⁶⁰Gd and a new type of shifted identical bands in ^156,158,160Sm as well as the first identical octupole bands in ^142,144Ba. Other new level structures are found. Yields and neutron multiplicities were measured directly for Sr---Nd, Zr---Ce, Mo---Ba, Ru---Xe, and Pd---Te correlated pairs. A new ultra hot fission mode was discovered going via only ¹⁰⁸Mo---¹⁴⁴Ba, ¹⁰⁷Mo---¹⁴⁵Ba, and/or ¹⁰⁶Mo---¹⁴⁶Ba pairs where one or more of ^44,145,146Ba are hyperdeformed at scission with 3:1 axis ratio.