The database for the 1930 Census has in Brookings Co., SD:

ANDERSON, Soren, b. ca. 1883
Amand {sic}, 1897
Florene J., 1914; Marion C.., 1917; Beula E., 1919, & Harlie E., 1921.

Social Security Death Index:

ANDERSON, Soren (25 Aug. 1883 - Nov. 1973, last res. Bruce, Brookings, SD) SSN issued SD.
ANDERSON, Marion (15 Nov. 1916 - July 1982, last res. Veblen, Marshall Co., SD) SSN issued SD.

Perhaps their obituaries would help you find the others.