Mansfield CA, Pattanayak SK, McDow W, MacDonald R, Halpin P. Shades of green: measuring the value of urban forests in the housing market. J Forest Econ. 2005 Dec;11(3):177-99. doi: 10.1016/j.jfe.2005.08.002
Hartman M, Bolton E, Fehnel SE. Accounting for age differences on the Wisconsin Card Sorting Test: decreased working memory, not inflexibility. Psychol Aging. 2001 Sep 1;16(3):385-99.