 It also makes appearances in the works of Elzbieta Adamczyk, Jonathan Slocum, and Winfred P. Lehmann.Several historical linguists have pointed towards the apparent material and social continuity connecting the cultures of the Nordic Bronze Age (1800 – 500 BC) and the pre-Roman Iron Age in Northern Europe (500 BC – 1 AD) as having implications in regard to the stability and later development of the Germanic language group.The emerging consensus among scholars is that the First Germanic Sound Shift, long considered to be "the" defining mark in the development of Proto-Germanic, happened as late as 500 BC.