D. Kafkewitz, C. R. Verhoest, M. L. Nucci, F. F. Davis, A. Abuchowski, T. Van Es, G. M. Kazo, A. T. Viau,
Cancer therapy with chemically modified enzymes. I. Antitumor properties of polyethylene glycol-asparaginase conjugates. Cancer biochemistry biophysics. ,vol. 7, pp. 175- 186 ,(1984)