Appendix B: Supplementary Measures of Timing: Standard and Poor's Data

Victor Zarnowitz, Orders, Production, and Investment: A Cyclical and Structural Analysis (NBER, 1973), https://www.nber.org/books-and-chapters/orders-production-and-investment-cyclical-and-structural-analysis/appendix-b-supplementary-measures-timing-standard-and-poors-data.