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Tau Gamma Sigma was created on 1969-01-17.
Sigma Gamma Epsilon was created in 1915.
Sigma Gamma Chi was created in 1967.
Yes...Gamma Sigma Sigma is not an NPHC organization, therefore, you may be a member of it and an NPHC organization.
Gamma Sigma Zeta was created on 2000-02-02.