Webber, B., & Webber, M. (1991). Index to Postmarked Washington: An encyclopedia of postal history combining the counties of Asotin, Spokane, Whitman, and all names mentioned in the section on Railway post offices in Washington State, (volume 1) 1858-1987. Webb Research Group.
Trích dẫn kiểu Chicago (xuất bản lần thứ 7)Webber, Bert, và Margie Webber. Index to Postmarked Washington: An Encyclopedia of Postal History Combining the Counties of Asotin, Spokane, Whitman, and All Names Mentioned in the Section on Railway Post Offices in Washington State, (volume 1) 1858-1987. Medford, OR: Webb Research Group, 1991.
Trích dẫn kiểu MLA (xuất bản lần thứ 8)Webber, Bert, và Margie Webber. Index to Postmarked Washington: An Encyclopedia of Postal History Combining the Counties of Asotin, Spokane, Whitman, and All Names Mentioned in the Section on Railway Post Offices in Washington State, (volume 1) 1858-1987. Webb Research Group, 1991.