Roberts และผู้แต่งคนอื่นๆ. 2005. Environmental perceptions of backpackers in Thailand : implicationa for sustainable tourism. Field of Study Natural Resource Management, Mahidol University;
Roberts และผู้แต่งคนอื่นๆ. (2005) Environmental perceptions of backpackers in Thailand : implicationa for sustainable tourism . Mahidol University/Bangkok.
Roberts และผู้แต่งคนอื่นๆ. Environmental perceptions of backpackers in Thailand : implicationa for sustainable tourism. . Bangkok:Mahidol University, 2005.
Roberts และผู้แต่งคนอื่นๆ. (2005) Environmental perceptions of backpackers in Thailand : implicationa for sustainable tourism . Mahidol University/Bangkok.