Regesta Norvegica is a calendar of documents relating to Norwegian history in the Middle Ages. The series is currently planned to comprise eleven volumes covering the period until 1440. There is, however, no real reason for breaking off at this point and the editors have expressed the very reasonable wish that the series be extended until the Reformation in 1536, the event which modern Norwegian historians consider marks the end of the Middle Ages in Norway (see i.a. the current volume p. 8). The calendar supplements and augments Diplomatarium Norvegicum, the great national edition of Norwegian charters from before 1570.  As Diplomatarium Norvegicum is thematically, rather than strictly chronologically arranged--each volume often concentrating on charters from a specific archive, or concerning a specific topic or region--a chronological index is a great help to the users. Every single document published in Diplomatarium Norvegicum is or will be calendared in the relevant volume of Regesta Norvegica. Inevitably, some of these charters have been redated since their publication and the volumes of Regesta Norvegica accordingly feature lists of such redatings. In addition to the "mandatory" entries, Regesta Norvegica also lists relevant documents published elsewhere, such as the diplomataria of the other Nordic countries, the great collections of Hanseatic sources, or, from England, Rymer's Foedera, Calendar of the Close Rolls and Calendar of the Patent Rolls, to mention but a few of the more important. This inclusiveness makes the calendar very useful for all who work on medieval Scandinavian history, particularly during the political union of the three kingdoms in the late Middle Ages. Regesta Norvegica is published by the National Archives of Norway, Section for Source Publications, in collaboration with Kjeldeskriftkommisjonen ("commission on historical sources"). The first nine volumes are already accessible online, see , and eventually volume X will be.
Volume X of Regesta Norvegica is edited by Gunnar I. Pettersen of the National Archives of Norway, who previously edited volumes VII and IX.  It covers the years 1420 to 1430, but was originally meant to include the years 1431 to 1435 as well. It contains 1085 entries, of which about two-thirds concern documents previously published in Diplomatarium Norvegicum, with the remaining third coming from a variety of different publications. In addition, it has a list of 73 redated charters, or more than 10% of the charters from the period 1420 to 1430, which were previously published in Diplomatarium Norvegicum I-XXIII.  This is a most useful service and it is the inescapable conclusion that you should always consult Regesta Norvegica when using Diplomatarium Norvegicum, even if the redatings primarily affect the earlier volumes of the diplomatarium.
Pettersen follows the rules laid down in volume VIII and begins each summary with a characterization of the document based on internal criteria, e.g. "treaty," "agreement," "confirmation," etc., in accordance with a typology, which has been developed for the series. The typology, which is undergoing continuous revision and presently has more than 100 different types, is very usefully listed in the subject index (more below). After the initial characterization follows the names of the issuer and the recipient or beneficiary. The names of all Norwegians and all Norwegian place names are mentioned, whereas the names of non-Norwegian persons and places are mentioned only if they are of particular interest for Norwegian history. All subjects touched upon in the document are included in the summary, as well as all indications of quantities and prices. Where necessary, endnotes supply additional technical information. Following the elaborate summary, the calendar gives very succinct information about the transmission of the document (original/copy), the language used in the document, the archive that houses it, its reference, and the principal editions (if the document has been published more than once). All information is given in Modern Norwegian (bokmål).
The volume closes with an index of names (persons and places) and a subject index, which take up 98 and 83 pages respectively. The editor has taken great care with these indices that work very well together and they evidently represent a great deal of effort and research. The subject index is very useful, many entries giving cross references, e.g. the entry on "social markers" (608-609: adelspredikater og andre sosiale markører) with 43 cross references, or "consanguinity and family relations" (675: slektskaps- og familieforhold) with 60. The entry on "letters" (617-618: brev) begins with 121 cross references before listing 85 subcategories! Very useful indeed. Incidentally, the list of cross references to different types of letters also forms the typology used for characterizing the documents.
It is perhaps unfair to ask for more, but a list of languages used in the documents would be useful. Even if most of the documents are in Norwegian or one of the other Scandinavian languages, Latin and German documents are also quite frequent. The information on language is given under the summary of each individual document, but a list would be very handy.
Making a calendar of historical sources is not an easy task. Very detailed summaries, of the type adopted by Regesta Norvegica, require great knowledge and insight on the part of the editor, who must deal with a very wide spectrum of subjects in many different fields: political, economic, social and legal history, as well as genealogy, topography and local history, in addition to the traditional auxiliary sciences of medieval history, diplomatics, chronology, philology, sigillography, heraldry, etc. In the calendar under review, Gunnar I. Pettersen has amply demonstrated his expertise and done a great service to all students of Norwegian and Scandinavian history in the late Middle Ages. Any calendar of documents based on previous editions is bound to become out-of-date, as new discoveries of relevant documents are made and published in critical editions, and as some of the already known material is perhaps republished in better editions. This will inevitably happen to Regesta Norvegica too, but currently it is an essential tool and considering the sheer amount and quality of the information, it holds, it is likely to retain its value for a long time to come. We can only hope that the editors will have their pious wish fulfilled and the National Archives of Norway extends the series to its natural conclusion, the Reformation in 1536.
1. See Erika Harlitz Kern's review of Diplomatarium Norvegicum XXIII in The Medieval Review, at .
2. See Anders Winroth's review of Regesta Norvegica IX in The Medieval Review, at .
3. The digital Diplomatarium Norvegicum lists 696 charters from the period 1420 to 1430 published in vols. I-XXI, to which must be added five charters from the same period published in vol. XXIII that is not part of the digital edition, see and Tor Ulset. Diplomatarium Norvegicum XXIII (Oslo: Riksarkivet, 2015), pp. 85-89, nos 80, 81 and 83-85. No. 82 has been redated to 1524, see Regesta Norvegica X, p. 40.