Secondary sources date the model to 1982, 1993 and 1999 and credit varying combinations of Heinich, Molenda, Russell and Smaldino as authors; a direct fetch of instructionaldesign.org, the most likely primary-adjacent source, returned HTTP 406 (system.BlockedFetch 1169).
What would resolve this The original edition of Heinich, Molenda, Russell (and later Smaldino)'s Instructional Media and Technologies for Learning, or a citation of it giving the exact first-edition year and author list.
OpenHistory of instructional designASSURE Instructional Design Model (Educational Technology)