My GreatGrandfather married my Greatgrandmother in Marshalltown in 1984.

His name was Walter David Anderson (d.o.b. 1862 in Sweden, and he arrived in the US in 1870)and her name was Bertha Olson (d.o.b. 1863 in Sweden, and she arrived in the US in 1867).

I am unable to find any information on Bertha.
I suspect that Henry (Henrick) Olsson was her brother, but this is merely supposition on my part.

Have you any idea(s) where I might be able to find valid information that may be of use to me?