GJ.716a, 1931 72c. Anniversary of the September revolution, pair, the right stamp with DOUBLE IMPRESSION, very rare and undervalued in the catalog (the estimate will be corrected in the next edition), very few known, excellent quality! (Image)

GJ.1256a + 1256 + variety, 1963 21P. Stylized Airplane, block of 10 with perforation VARIETY: the 4 left stamps with "ARGENTINA" at left (GJ.1256a), the next 2 are similar but much norrower, WITHOUT FACE VALUE, and the rest with the face value on the left and "ARGENTINA" in the center, spectacular! (Image)