John Nicholls. PL/I compile time extensibility. SIGPLAN Notices, 4(8):40-44, 1969. [doi]
@article{Nicholls69, title = {PL/I compile time extensibility}, author = {John Nicholls}, year = {1969}, doi = {10.1145/1115858.1115868}, url = {https://doi.org/10.1145/1115858.1115868}, researchr = {https://researchr.org/publication/Nicholls69}, cites = {0}, citedby = {0}, journal = {SIGPLAN Notices}, volume = {4}, number = {8}, pages = {40-44}, }