Childhood leukemia-lymphoma. Heterogeneity of phenotypes and prognoses.

Abstract

First day cover with four 26-cent airmail stamps honoring Mount Rushmore. The stamps feature a drawing of Mount Rushmore with blue sky and a red strip at the bottom with "USA" printed on it in white. Along the left side of the envelope is a black and white illustration of Mount Rushmore with a plane flying above the monument.