References:
Hartill 7.10ff
Schjöth 86,7

Notes:
Called Yu Jia, or 'elm seed' coins, these were a degenerate private mint issue, though under authority.

References:
Hartill 7.15
FD420

References:
Hartill 7.16
 

References:
Hartill 7.17

References:
Hartill 7.32

References:
None

Notes:
The reverse of this could be interpreted as 'yi er' or vice versa. 

References:
Hartill 8.8
Schjöth 115

Notes:
Bar above central hole.

References:
Hartill 8.9
 

References:
Hartill 8.10

Notes:
Half moon below central hole.

References:
Hartill 10.29 similar

Notes:
An interesting series of coins, it would seem that these are burial pieces.  Although dating has been something of debate, recent excavations show most of these coming from Han period tombs, indicating they at the least begin to be issued from that period.  They are always found in essentially mint state, showing that they were never intended for and were not likely ever in circulation.  these diminutive coins are commonly called 'goose eye' or 'chicken eye' coins.

References:
Hartill 10.3v

Notes:
Three lines on reverse instead of the normal four.

References:
Hartill 13.3

References:
Hartill 13.23

References:
Zhongguo Guqian Daji, pp279
Zhongguo Qian Bi Da Ci Dian----

Notes:
General consensus of the community is that this is an altered coin.  I have been told that the Chinese have the ability to take ground patina and mix it with other elements and apply the mixture to a genuine coin and mould or otherwise form a new character.  Scott Semans has suggested that if I boil the coin, the false character should dissolve.  I have yet to take the time to perform this test.  If genuine, it would be one of just a few examples known.  Daji assigns it to the Six Dynasties period and says that their specimen was found in the Jiangsu area.  Dian does not date their example, but mentions that it was found in Zhedong.

References:
None

Notes:
Another doubtful coin.  Plucked from a large group of Wu Zhu's years ago.  The first time this coin was presented to the community, all agreed it was genuine.  The second time I presented it for attribution, a number of people felt it was false.  This type is primarily known from contemporary literature as well as a mould excavated in 1935 (showing four lines radiating from the corners of the central square).  The dating and attribution of the type is contested, though odd variations of the Wu Zhu mostly appear in the North & South Dynasties period of the 5th to 6th Century AD.  It has been theorized that this type is not a coin but rather a charm of the period. 

References:
Hartill 13.27

References:
Hartill 13.29

References:
Hartill 13.30

References:
Hartill 13.30

References:
Hartill 15.134