672 and 672a (CSS 1043 and 1043A) design size and a perforation study on unwatermarked paper and a Canton to USA cover. (There is a typo on 1043A in the CSS Catalog. It should read 639c instead of 536d)

672 and 672a (CSS 1043 and 1043A) design size and a perforation study on unwatermarked paper and a Canton to USA cover. (There is a typo on 1043A in the CSS Catalog. It should read 639c instead of 536d)