Looking for Ole Bakken and Rennog "Rena" Peterson

I am looking for ancestors, Ole Bakken married to Rennog "Rena" Peterson. I have a 1900 Census or Elk Point South Dakota which states that Ole and Rena are the parents of 13 children, with 8 living. They immigrated from Norway in 1885. Ole was born in 1850, Rena in 1853. I have come across posting at Rootsweb which state that their daughter Christine was born in Trondheim, Sor-Trondelag, Norway. Ole and Rena's children are: Mathias born 1879, Martha born 1880, Christina born 1882, Eli born 1885, Rena born 1888, Bertha born 1890, Alfred born 1892, Oscar born 1896, and Frank no dates. I do not have information on the 5 other children, so i do not know if they died in Norway, on board ship or in the United states. Any information would be most helpful. Lori