diff --git a/README.md b/README.md
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@@ -8,7 +8,7 @@ A list of references on lidar point cloud processing for autonomous driving
 * An Improved RANSAC for 3D Point Cloud Plane Segmentation Based on Normal Distribution Transformation Cells
 * Segmentation of Dynamic Objects from Laser Data [[pdf](https://upcommons.upc.edu/bitstream/handle/2117/14119/1259-Segmentation-of-Dynamic-Objects-from-Laser-Data.pdf?sequence=1&isAllowed=y)]
 * Fast semantic segmentation of 3d point clounds with strongly varying density [[pdf](https://www.ethz.ch/content/dam/ethz/special-interest/baug/igp/photogrammetry-remote-sensing-dam/documents/pdf/timo-jan-isprs2016.pdf)]
-* A Fast Ground Segmentation Method for 3D Point Cloud [[pdf](jips-k.org/file/down?pn=463)]
+* A Fast Ground Segmentation Method for 3D Point Cloud [[pdf](http://jips-k.org/file/down?pn=463)]
 * Ground Estimation and Point Cloud Segmentation using SpatioTemporal Conditional Random Field [[pdf](https://hal.inria.fr/hal-01579095/document)]
 * Real-Time Road Segmentation Using LiDAR Data Processing on an FPGA [[pdf](https://arxiv.org/pdf/1711.02757.pdf)]
 * Efficient Online Segmentation for Sparse 3D Laser Scans [[pdf](http://www.ipb.uni-bonn.de/pdfs/bogoslavskyi16pfg.pdf)], [[git](https://github.com/PRBonn/depth_clustering)]