Stuart H. Zweben, Maurice H. Halstead. The Frequency Distribution of Operators in PL/I Programs. IEEE Trans. Software Eng., 5(2):91-95, 1979.
@article{ZwebenH79, title = {The Frequency Distribution of Operators in PL/I Programs}, author = {Stuart H. Zweben and Maurice H. Halstead}, year = {1979}, researchr = {https://researchr.org/publication/ZwebenH79}, cites = {0}, citedby = {0}, journal = {IEEE Trans. Software Eng.}, volume = {5}, number = {2}, pages = {91-95}, }