# External Human-Machine Interfaces: Which of 729 Colors Is Best for Signaling ‘Please (Do not) Cross’?

> Research article (2020 IEEE International Conference on Systems, Man, and Cybernetics (SMC), 2020) · cited 44× · AI/ML

**Wikidata**: [openalex:W3111667030](https://www.wikidata.org/wiki/openalex:W3111667030)  
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