“People, when initially introduced to structures, also referred
to as Archetypes, often find them a bit overwhelming. They really
aren't at all difficult once you get used to them. The following
is an introduction to structures and how to read the stories associated
with the diagrams.”

http://www.systems-thinking.org/intst/int.htm

Be sure to work upstream in the URL to see the rest of Bellinger's work.