Philately.
a block of four or more U.S. stamps that includes, in the selvage of the sheet, the copyright mark of the U.S. Postal Service.
Philately.
a block of four or more U.S. stamps that includes, in the selvage of the sheet, the copyright mark of the U.S. Postal Service.
Random House Webster's Unabridged English dictionary. Полный английский словарь Вебстер - Random House . 2012