Lawrence G. Roberts. A graphical service system with variable syntax. Communications of the ACM, 9(3):173-176, 1966. [doi]
@article{Roberts66,
title = {A graphical service system with variable syntax},
author = {Lawrence G. Roberts},
year = {1966},
doi = {10.1145/365230.365259},
url = {http://doi.acm.org/10.1145/365230.365259},
researchr = {https://researchr.org/publication/Roberts66},
cites = {0},
citedby = {0},
journal = {Communications of the ACM},
volume = {9},
number = {3},
pages = {173-176},
}