APA (7th ed.) Citation

Reyos, D. A., & Tan, E. L. On graceful, residually graceful and properly graceful digraphs.

Chicago Style (17th ed.) Citation

Reyos, Diana A., and Evelyn L. Tan. On Graceful, Residually Graceful and Properly Graceful Digraphs.

MLA (9th ed.) Citation

Reyos, Diana A., and Evelyn L. Tan. On Graceful, Residually Graceful and Properly Graceful Digraphs.

Warning: These citations may not always be 100% accurate.