Hi Don, assuming that this is your great-grandfather's family in the 1930 census:
Name: Olef Norlender [Olif Norlender]
Birth Year: abt 1893
Gender: Male
Race: White
Birthplace: Sweden
Marital Status: Married
Relation to Head of House: Head
Home in 1930: Duluth, St Louis, Minnesota
Map of Home: View Map
Street address: Fourth Street West
Ward of City: Precincts 40, 41 and 42
House Number in Cities or Towns: 1901
Dwelling Number: 237
Family Number: 320
Home Owned or Rented: Rented
Home Value: 19
Radio Set: No
Lives on Farm: No
Age at First Marriage: 20
Attended School: No
Able to Read and Write: Yes
Father's Birthplace: Sweden
Mother's Birthplace: Sweden
Language Spoken: Swedish
Immigration Year: 1910
Naturalization: First Papers
Able to Speak English: Yes
Occupation: Cament Worker
Industry: Street Construction
Class of Worker: Wage or salary worker
Employment: Yes
Neighbors: View others on page
Household Members:
Name Age
Olef Norlender 37
Gerda Norlender 43
Margaret Norlender 17
William Norlender 10
...the birth record for Margaret (source Minnesota Historical Society
http://people.mnhs.org/finder/bci/1913-50153) lists her mother's maiden name as Peterson:
Norlander, Margaret Ann
Birth Certificate Index
Certificate Number: 1913-50153
Birth: April 13, 1913
County of Birth: St. Louis County, Minnesota, United States
Subject: Birth records
Type: Text, Government Record, Historical Records
Mother's Maiden Name: Peterson
Gerda's name is also listed as Peterson in this record for their son William Norlander from Ancestry.com:
U.S., Social Security Applications and Claims Index, 1936-2007
Name: William Anton Norlander [William A Norlander]
SSN: 469148000
Gender: Male
Race: White
Birth Date: 26 Jan 1920
Birth Place: Two Harbors, Minnesota
Father Name: Olaf E Norlander
Mother Name: Gerda Peterson
Death Date: 4 May 2002
Type of Claim: Original SSN.
Notes: Jan 1938: Name listed as WILLIAM ANTON NORLANDER; 10 May 2002: Name listed as WILLIAM A NORLANDER
On the Emibas CD there's a Gerda Maria Petersson from Gullabo who emigrated in 1904 but she has a different birth date:
Post 298532
Petersson, Gerda Maria
Unmarried woman
b. 4/12/1885 in Gullabo, Kalmar län (Småland)
Emigrated 4/28/1904 from Glosebo 1, Gullabo, Kalmar län (Småland) to Amerika
Source: Household Examination Roll, p. 124
Emibas migration file ID: Gullabo H 1904 011
Gerda was actually born in Torsås though (Torsås CI:11 (1876-1894) Bild 126).
The Swedish Immigrant/Emigranten CD shows this woman emigrated to Thomson, Minnesota:
First name: GERDA M
Last name: PETERSSON
Age: 19 Gender: K
Parish: GULLABO County: H
Port: MALMÖ
Date: 1904 05 04
Destination: THOMSON MN
Fellows: NEJ
Source: 1904:1064:4239
Could this be your Gerda? The Sweden Indexed Birth Records index at Ancestry.com has a Gerda Maria born 13 Oct 1887 but I don't think she's the correct person since she probably wouldn't have used the name Peterson.
Child's Given Name: Gerda Maria
[Gerda Maria Söderman]
[Gerda Maria Johannesdotter]
Birth Date: 13 okt 1887 (13 Oct 1887)
Birth Place: Rådmansö, Stockholm, Sweden
Father: Johannes Söderman
Mother: Carolina Jansdotter
Mother Birth Date: abt 1847
Mother Age: 40
GID Number: 100001.68.17300
Roll/Fiche Number: SC-491
Volume: :884