Notes on procedure:

Where duration of an outbreak is clearly reported, the symbol for "documented outbreak" has been marked on the map, and where the outbreak is hard to date exactly, or poorly documented, a "undocumented or possible outbreak" symbol is used.

Where outbreaks are not clearly indicated to have an end date, or documentation for the duration of an outbreak is otherwise lacking, I have assumed that an outbreak lasts at least four months, and marked it as such. Thereafter, I have marked the same location as a "possible or undocumented" outbreak location for another four months. The basis of this (admittedly arbitrary) system is the observation that most plague outbreaks seem to have lasted 5-7 months. Therefore, in the absence of specific data, I have assumed four months as an absolute minimum duration (marking them as "documented", and eight as a conservative maximum (marking the remaining four as "poorly documented").

Where only approximate times for an outbreak are listed (i.e. a particular season or a particular year), I have attempted to err on the side of caution. In general, where an outbreak can be determined only as having occurred in a particular year, I have let myself be guided by the outbreak pattern in nearby localities. In the source column, these interpolations are marked with the note (ip).

Finally, where regions are cited as the location of an outbreak, rather than individual point locations, I have chosen to mark the outbreak as taking place in the major city of the region. Data points attributed in this way are marked in [box brackets].

Documented outbreak periods are listed in plain text in the "Outbreak(s)" column, possible/undocumented outbreak periods in emphasis.

As of the latest revision, there are 184 data points marked in - the criterion for satisfactory completion has been (arbitrarily) set at approx. 170-220 data points.

The sparsity of sources is always a problem when working with this subject. Some areas, such as parts of Poland and the Low Countries, have few or no recorded instances of plague. On the maps, these necessarily show up as an absence of data points. Nevertheless, it would probably be a mistake to conclude from the lack of sources that these regions were totally unaffected by the Black Death. Bear in mind, therefore, when reading the maps, that they display only positive knowledge, and are by necessity incomplete.

Sources (in reverse order of publication):

MHG - Michael H. GELTING: Coping with the Black Death (As yet unpublished MS, 2000)

PZ - Phillip ZIEGLER: The Black Death (London 1969, 2nd ed. 1998)

OJB - Ole Jørgen BENEDICTOW: Plague in the Late Medieval Nordic Countries (Oslo 1992)

EU - Erik ULSIG: "Pest og befolkningsnedgang i Danmark i det 14. århundrede" in Historisk Tidsskrift (Copenhagen 1991)

JNB - Jean-Noël BIRABEN: Les hommes et la peste en France et dans les pays européens et méditerranéens - Tome I, La peste dans l'histoire (Paris 1975)