Risk of acute nonlymphocytic leukemia and preleukemia in patients treated with cyclophosphamide for non-Hodgkin's lymphomas: comparison with results obtained in patients treated for Hodgkin's disease and ovarian carcinoma with other alkylating agents - Pedersen-Bjergaard,J.; Ersbøll,J.; Sørensen,H.M. (Ann Intern Med, 1985)