[1] [CITE@en[January 0 - Wikipedia]]
([TIME[2017-01-05 18:35:14 +09:00]])
<https://en.wikipedia.org/wiki/January_0>

[2] [CITE@ja[1月0日 - Wikipedia]]
([TIME[2018-02-19 13:04:43 +09:00]])
<https://ja.wikipedia.org/wiki/1%E6%9C%880%E6%97%A5>