Παραπομπή σε μορφή APA (7η εκδ.)

Ryan, K. (1993). Trails for the twenty-first century: Planning, design, and management manual for multi-use trails. Island Press.

Παραπομπή σε μορφή Chicago (17η εκδ.)

Ryan, Karen-Lee. Trails for the Twenty-first Century: Planning, Design, and Management Manual for Multi-use Trails. Washington D. C.: Island Press, 1993.

Παραπομπή σε μορφή MLA (9th εκδ.)

Ryan, Karen-Lee. Trails for the Twenty-first Century: Planning, Design, and Management Manual for Multi-use Trails. Island Press, 1993.