A thesis by publication, also known as an essay thesis or an article thesis, is a doctoral dissertation that, as opposed to a coherent monograph, is a collection of research articles with an introductory and a summary chapter. It comprises already-published journal articles, conference papers and book chapters, and occasional not yet published manuscripts. A thesis by publication is a form of compilation thesis (a term used in Nordic countries). A less common form of compilation thesis is an essay thesis, comprising previously unpublished independent essays.