Investigating Andreasen tree - help!

I'm in the middle of researching my Norwegian heritage and have hit a snag. I figure this forum is full of experts, so why not try here?! I've actually found records from family members but am not sure how to go about finding dates of death for certain members. All I have to go on is a birth date and am not sure if it's accurate. Here's what I do know. Mother: Karen (Caren?) Olin Pedersdatter Father: Andreas Johannesen Children: Johan? (1864) Gudbrand (1865) Marthin ( 1869)? Anthon (1870)? Gyda (1874) Lars (1876) What's the best way to find a date of death? I've done preliminary searches but these names are so common in Norway. HELP!