I found an example from the University of Umeå written by Lisbeth Lundahl. It is published as a 'work in progress' but I find it very helpful. The title is in Swedish but the text in English. Possibly papers like this are produced for the use of the doctoral students within each institution. It seems that the expectations for a summary, or 'kappa' as it is called in Scandinavia differs between countries and even between institutions.
Lisbeth Lundahl is professor in Applied Educational Science. She writes:
"Writing a thesis made up by a compilation of articles with some kind of embracing text is a rather new phenomenon in our field of research. Writing this latter text, the kappa, is not seldom perceived as an unclear and problematic task for PhD students and their supervisors."