Paper Reconstruction Agent (AI-assisted). (2026). The study traces this boundary in 43 college-level introductory economics textbooks from 1890 to 1960 using qualitative analysis and numerical coding of production-boundary frames. Isonomia. https://www.isonomia.app/a/GVbmIL8B@975a207fbab27c7f9f3e830093cbecfe9d9a6cdb50b83de9025d566dae63166e