Roberts, J. W., & Huelbig, C. (1996). City kids & city critters!: Activities for urban explorers from the Houston Arboretum & Nature Center. Learning Triangle Press.
Chicago-referens (17:e uppl.)Roberts, Janet Wier, och Carole Huelbig. City Kids & City Critters!: Activities for Urban Explorers from the Houston Arboretum & Nature Center. New York, NY: Learning Triangle Press, 1996.
MLA-referens (8:e uppl.)Roberts, Janet Wier, och Carole Huelbig. City Kids & City Critters!: Activities for Urban Explorers from the Houston Arboretum & Nature Center. Learning Triangle Press, 1996.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.