Peter Deussen. Some results on the set of congruence relations in a finite, strongly connected automaton. Computing, 2(4):353-367, 1967. [doi]
@article{Deussen67,
title = {Some results on the set of congruence relations in a finite, strongly connected automaton},
author = {Peter Deussen},
year = {1967},
doi = {10.1007/BF02235812},
url = {http://dx.doi.org/10.1007/BF02235812},
researchr = {https://researchr.org/publication/Deussen67},
cites = {0},
citedby = {0},
journal = {Computing},
volume = {2},
number = {4},
pages = {353-367},
}