As we have talked to people about this project, there has been interest in books and websites we have been referencing. This file will be updated periodically with references for the project. 

College Board report on results of AP Calculus exams:

Characteristics of Successful Programs in College Calculus - Publications & Reports, Math Association of American

National Academy of Sciences report on barriers and opportunities on 2- and 4-year STEM degrees:

Our books, 3D Printed Science Projects (first volume)

and Volume 2:

Principia, photographs of Newton’s copy

Definitive translation with commentary:

Jo Boaler, Mathematical Mindsets

Calculus Made Easy Revised, Updated, Expanded Edition
In print since 1910
by Silvanus P. Thompson (Author), Martin Gardner (Author)