Death Traps to Treasure: Spanish and Mexican Mine Traps, Warning Signs and Symbols

Treasure Signs, Symbols, Shadow and Sun Signs

Spanish Monuments and Trailmarkers to Treasure in the United States

Turtles Lead to Treasure: A Guide to Spanish Trail Monuments

Commander's Cacheology Encyclopedia of Treasure Symbols: Ancient Symbols: Detailed and Decoded leading to Lost Treasures

Handbook of Treasure Signs and Symbols