diff --git a/20250227-what-is-rank-in-matrix/what-is-rank-in-matrix.md b/20250227-what-is-rank-in-matrix/what-is-rank-in-matrix.md
index 7a5e7c7..2fd301f 100644
--- a/20250227-what-is-rank-in-matrix/what-is-rank-in-matrix.md
+++ b/20250227-what-is-rank-in-matrix/what-is-rank-in-matrix.md
@@ -84,4 +84,4 @@ $\|A - A_k\|_F \leq \sqrt{\sum_{i=k+1}^r \sigma_i^2}$
 
 ## Refs
 
-* [Data-driven methods for reduced-order modeling](https://www.researchgate.net/publication/347692023_7_Data-driven_methods_for_reduced-order_modeling)
+* [7 Data-driven methods for reduced-order modeling](https://www.researchgate.net/publication/347692023_7_Data-driven_methods_for_reduced-order_modeling)