title: Introduction to electron crystallography.
abstract: This introduction describes the contributions to this topical issue, and in some cases gives observations on the importance and implications of these articles. Subsequently, there is a discussion of the phase problem and its solution using the unitary equation. This equation, which is true for all known scattering processes, provides a firm theoretical basis for the direct methods of phasing.
authors.affiliation: Wadsworth Center, Albany, New York 12201-0509, USA. william.tivol@wadsworth.org
authors.forename: W F
authors.initials: WF
authors.lastname: Tivol
mesh_terms: D003461:Crystallography / Q000379:methods*; D008854:Microscopy, Electron / Q000295:instrumentation* / Q000379:methods*