1.		An ecotourism perspective on billfish fisheries / Stephen M. Holand, Robert B. Ditton, Alan R. Graefe Autor: Holland, Stephen M. Coautor: ; Ditton, Robert B. Graefe, Alan R.
2.		A response to ecotourism on trial : the case of billfisf angling as ecotourism / Stephen M. Holland, Robert B. Ditton, Alan R. Graefe Autor: Holland, Stephen M. Coautor: ; Ditton, Robert B. Graefe, Alan R.