How <a href="https://en.wikipedia.org/wiki/collateralized_debt_obligations" class="extiw" title="w:collateralized debt obligations">collateralized debt obligations</a> are structured
National Commission on the Causes of the Financial and Economic Crisis in the United States
"<a rel="nofollow" class="external text" href="https://www.gpo.gov/fdsys/pkg/GPO-FCIC/pdf/GPO-FCIC.pdf">Final Report of the National Commission on the Causes of the Financial and Economic Crisis in the United States</a>", p.128 figure 8.1