[Soil survey report] series 1937, 19 and 20. 19. Soil survey, Snohomish County, Wash.; by A. C. Anderson, C. C. Nikiforoff, W. J. Leighty, L. L. Anderson, E. H. Hubbard, H. J. Maker, H. A. Olsen, R. F. Pasco, and C. T. Waldo.