APA

U.S. Internal Revenue Services, . (19). Package X; informational copies of Federal income tax forms. Washington: U.S. Govt. Print. Off.

Chicago

U.S. Internal Revenue Services, . 19. Package X; informational copies of Federal income tax forms. Washington: U.S. Govt. Print. Off.

Harvard

U.S. Internal Revenue Services, . (19). Package X; informational copies of Federal income tax forms. Washington: U.S. Govt. Print. Off.

MLA

U.S. Internal Revenue Services, . Package X; informational copies of Federal income tax forms. Washington: U.S. Govt. Print. Off. 19.