References:
Hartill 1.4
Schjöth15-17
FD4

Notes:
While the inscription on this coin is uncertain, the most common interpretation is Bei, or shell, which could be a transition from the original cowrie shell to bronze.  As such, it could be argued that this type is the first proper 'coin', though the definition of that word is highly debatable and without common consensus.  I personally do classify this type as an early coin, and not as 'primitive' as others might.

References:
Hartill 6.17
Schjöth 77
FD 382

Notes:
Although Hartill ascribes the new Yi Hua to this coin, Yi Dao remains a very popular reading of the inscription.

References:
Hartill 6.20
FD 384

References:
Hartill 7.3
FD 385-7
Jen 46

References:
Hartill 7.4

Notes:
'Rosette' hole.  This example is uncleaned and in a rather natural state of preservation.  Unfortunately, the photograph is unable to show the beautiful and fascinating crystallization of the surfaces, which is very attractive in its own right.

References:
Hartill 7.6
Schjöth 88
FD 385-7