Paul Penfield Jr.. APL symbols. ACM SIGAPL APL Quote Quad, 6(1):36, 1975. [doi]
@article{Penfield75-0,
title = {APL symbols},
author = {Paul Penfield Jr.},
year = {1975},
doi = {10.1145/585923.585930},
url = {https://doi.org/10.1145/585923.585930},
researchr = {https://researchr.org/publication/Penfield75-0},
cites = {0},
citedby = {0},
journal = {ACM SIGAPL APL Quote Quad},
volume = {6},
number = {1},
pages = {36},
}