Here is another start of a reading list on the concept and estimation of trends in economics. This is a selection from JSTOR on very early papers on trends and trend fitting. The literature is immense so some time is required to complete this list. We put some of later papers as well at the end of this list and they will be moved in their right place as we progress with this project (moved already!)

1. On the Variate Difference Correlation Method and Curve-Fitting, Publications of the American Statistical Association, 1917.
2. Measurement of Cyclical and Irregular Fluctuations, The Review of Economics and Statistics, 1919.
3. The Line of Secular Trend, The Review of Economics and Statistics, 1919.
4. Measurement of Secular Trend, The Review of Economics and Statistics, 1919.
5. General Considerations Relating to Secular Trend , 1903-18, The Review of Economics and Statistics, 1919.
6. Measurement of Cyclical and Irregular Fluctuations , The Review of Economics and Statistics, 1919.
7. Secular Trends and Business Cycles: A Classification of Theories , The Review of Economics and Statistics, 1922.
8. The Determination of Secular Trend Reconsidered, Journal of the American Statistical Association, 1922.
9. Secular Trends and Business Cycles: A Classification of Theories, The Review of Economics and Statistics, 1922.
10. The Determination of Secular Trend , Journal of the American Statistical Association, 1922.
11. Cycles and Trends in Economic Factors , The Review of Economics and Statistics, 1923.
12. Seasonal Variation as a Relative of Secular Trend , Journal of the American Statistical Association, 1924.
13. A Moving Secular Trend and Moving Integration, Journal of the American Statistical Association, 1925.
14. The Error in Eliminating Secular Trend and Seasonal Variation Before Correlating Time Series, Journal of the American Statistical Association, 1925.
15. The Least Squares Criterion for Trend Lines, Journal of the American Statistical Association, 1925.
16. The Determination of past and Present Secular Trends , Journal of the American Statistical Association, 1926.
17. The Trend-Seasonal Normal in Time Series , Journal of the American Statistical Association, 1926.
18. On the Logic of the Decomposition of Statistical Series into Separate Components , Journal of the Royal Statistical Society, 1927.
19. The Problem of Secular Trend, The Review of Economics and Statistics, 1934.
20. The Secular Trend in Income Distribution by Type, 1869-1948: A Preliminary Estimate, The Review of Economics and Statistics, 1953.