The Calendar for Thia Frankisk Aldsido is called the Fîringatal ( Recounting of Celebrations) and is devised through the application of comparative research as well as principles of religious observation. The primary sources for developing the Fîringatal are:
Calendar of 354: Also known as the Chronographia of 354 or the Calendar of Philocalus, is a record of 4th century civic holidays observed by the Western Roman Empire. The calendar is of principle interest as it was preserved by later Carolingians as an important cultural work. The calendar provides an interesting view of Roman civic religion at the advent of Christianity. Being that the calendar was surely known throughout the major Gallic centres, by the nobility and other learned people, there is little doubt that it was also known by Merovingian rulers of that age. The calendar also lists holidays or celebrations that would have been widely observed throughout the empire and as such, most likely relevant to Romanized Germans on the limes. The holidays also follow a logical seasonal flow of activities, where martial, agricultural and mercantile gods were worshipped at times which made logical sense. This seasonal flow of activities were not exclusive to the Romans, thus the logical progression of the months would have also been followed by the early Franks.
Ovid’s Fasti: Ovid’s Fasti, the books which have come down to us, provide context for the celebrations we encounter in the Calendar of 354. By fleshing out these observances, we can intuit cognates in the Frankish fragments we have left to us. At times, the similarities between the Ovidian Roman god and the Gallo-Germanic god are far too eerily similar to ignore.
Gregory of Tours: The History of the Franks by Gregory, offer us important social contexts and narrative frames useful in ensuring that the TFA celebrations are culturally aligned with the ways of the elder Frank.
Liber Historia Francorum: As this anonymous work provides us with the bulk of the Franco-Trojan Cycle, we can look to this history as a comparative to the journeys of Aeneas.
Chronicle of Fredegar (IV): This chronicle by the pseudo-Fredegar offers an important look into the lineage of the Merovingians and helps tie their mythic rise to that of comparative PIE peoples.
There are many more sources to list, however they have been listed in the copious endnotes for each of the months.