How to match period and space?

[Peng Yu]

Hi,

$ ls
a.b.txt  a_b.txt

I have the above two files.  I am trying to use [] to match a point
character or a space character. But it does not work. How can I match
both a period character and a space character?

$ ls *[.' ']*.txt
a.b.txt

-- 
Regards,
Peng