An index is useful for complex works of non-fiction and academic books because it allows the reader to quickly access specific topics and references. (bbebooksthailand.com)
We then move our students through more complex work in geometry and algebra in the middle grades to enrich and develop confidence, excellence, and preparedness for high school math. (hellothinkster.com)
As a result of that, I've had to learn some really complex work in finance and operations so I can speak confidently with other executives and get things done. (topmargin.com)