unregular

References in classic literature ?
I must lay it by in my mind, and think it over some time or other, it's so kind of strange and unregular.
Leave everything, all the hurting stuff, the unregular stuff that seemed so regular to me, in the dust.
This shows that the distribution of species is unregular in March and December and regular between May and September.
Although the used PUR adhesive performed well, the sieve surface obviously was too unregular to perform better.
Another source is claimed to be unregular cleaning of street dust and construction mud (during the summer).