The coins covered by N# 181 have two Schön numbers, and the current listing doesn't have either of them.
Half Franc coins before 1968 are KM# 23, Schön# 27.
1968 to 1982 are KM# 23a, Schön# 27a. (The current listing says Schön# 27.)
In 1983 the design was changed, the number of stars changed. Schön noticed this and those coins are Schön# 57. KM called this a minor change on the design and called it KM# 23a.3.
Why is it appropriate to not have Schön# 57 in the reference number list?