Spring, I., & Manning, H. (1974). Wilderness trails Northwest: A hiker's and climber's overview-guide to national parks and wilderness areas in Wyoming, Montana, Idaho, Northern California, Oregon, Washington, British Columbia, Canadian Rockies. Touchstone Press.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Spring, Ira, و Harvey Manning. Wilderness Trails Northwest: A Hiker's and Climber's Overview-guide to National Parks and Wilderness Areas in Wyoming, Montana, Idaho, Northern California, Oregon, Washington, British Columbia, Canadian Rockies. Beaverton, Or.: Touchstone Press, 1974.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Spring, Ira, و Harvey Manning. Wilderness Trails Northwest: A Hiker's and Climber's Overview-guide to National Parks and Wilderness Areas in Wyoming, Montana, Idaho, Northern California, Oregon, Washington, British Columbia, Canadian Rockies. Touchstone Press, 1974.