1) Pat S. Chavez, Jr., Digital Merging of Landsat TM and Digitized NHAP Data for 1: 24,000-Scale Mapping, Photogrammetric Engineering and Remote Sensing, vol.52, no.10 (1986)
2) R. Welch and Manfred Ehlers, Merging Multi-resolution SPOT and Landsat TM Data, Photogrammetric Engineering and Remote Sensing, vol. 52, no, 3 (1987)