“PROOF WITHOUT WORDS: $\frac{a}{b}=\frac{c}{d} \Rightarrow \frac{a}{b}=\frac{c}{d}=\frac{a \pm c}{b \pm d}$ IN THE RANGE OF NATURAL NUMBERS”. Far East Journal of Mathematical Education 22 (June 15, 2022): 29–32. Accessed January 5, 2026. https://pphmjopenaccess.com/fejme/article/view/666.