Stable Analysis Patterns. Computer Science and Engineering Dept., University of Nebraska-Lincoln. http://hillside.net/plop/plop2002/final/PLoP02-A%20Patter
“Relations between soil colour and waterlogging duration in a representative hillside of the West African granito-gneissic bedrock” (PDF). Catena 39 (3): 187-210
University of Kentucky. 1943年. 2015年3月31日閲覧. ^ Hillside Steps. Department of Transportation and Engineering, City of Cincinnati. 2015年3月31日閲覧. ^ Inclines