Radosevich JA, Gould VE, Ma Y, Lee I, Thor A, Carney WP, Warren WH, Schlom J, Rosen ST. Immunohistochemical analysis of normal and mutated ras oncogene p21 expression in human pulmonary and pleural neoplasms. Virchows Arch B Cell Pathol Incl Mol Pathol. 1989; 56(6):377-83.