Reference
Hartill GCC : Page 108, cf ## 2.153 and 2.155, but with 道 and 寶 switched
Note:
This example is not included in Hartill's GCC. However, its style is clearly allied to # 2.153 and # 2.155 in Hartill's category: Large Copper - Resembling Song Dynasty Chinese coins. However the coin appears to be made of tin and has the characters 道 and 寶 switched.