The material contained in this series consists of data files from a database, research data, and files that describe how different software programs work. These files can be opened using Notepad or Wordpad. Also included are 11 DAT files that contain numerical data. There are five folders listed on the published finding aid listed with NMRI in the folder title; these files could relate to these folders. The original files are undated, but materials were transferred to the Archives in 2012 after Lambertsen's death in 2011.