APA

Library of Congress, .Directory of producers of accessible reading materials. Washington, DC: National Library Service for the Blind and Physically Handicapped, Library of Congress.

Chicago

Library of Congress, .Directory of producers of accessible reading materials. Washington, DC: National Library Service for the Blind and Physically Handicapped, Library of Congress.

Harvard

Library of Congress, .Directory of producers of accessible reading materials. Washington, DC: National Library Service for the Blind and Physically Handicapped, Library of Congress.

MLA

Library of Congress, .Washington, DC: National Library Service for the Blind and Physically Handicapped, Library of Congress. .