"Alf, Martha, 1930-". LC Linked Data Service: Authorities and Vocabularies (Library of Congress). Library of Congress. مؤرشف من الأصل في 2017-12-02. اطلع عليه بتاريخ 2017-12-02.
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"Alf, Martha, 1930-". LC Linked Data Service: Authorities and Vocabularies (Library of Congress). Library of Congress. مؤرشف من الأصل في 2017-12-02. اطلع عليه بتاريخ 2017-12-02.