Update README.md

Author: hoya012

README.md

@@ -237,15 +237,15 @@ The papers related to datasets used mainly in Object Detection are as follows.
 
 - **[PASCAL VOC]** The PASCAL Visual Object Classes (VOC) Challenge | Mark Everingham, et al. | **[IJCV' 10]** | [`[pdf]`](http://host.robots.ox.ac.uk/pascal/VOC/pubs/everingham10.pdf)
 
-- **[PASCAL VOC]** The PASCAL Visual Object Classes Challenge: A Retrospective | Mark Everingham, et al. | **[IJCV' 15]** | [`[pdf]`](http://host.robots.ox.ac.uk/pascal/VOC/pubs/everingham15.pdf)
+- **[PASCAL VOC]** The PASCAL Visual Object Classes Challenge: A Retrospective | Mark Everingham, et al. | **[IJCV' 15]** | [`[pdf]`](http://host.robots.ox.ac.uk/pascal/VOC/pubs/everingham15.pdf) | [`[link]`](http://host.robots.ox.ac.uk/pascal/VOC/)
 
 - **[ImageNet]** ImageNet: A Large-Scale Hierarchical Image Database | Jia Deng, et al. | **[CVPR' 09]** | [`[pdf]`](http://www.image-net.org/papers/imagenet_cvpr09.pdf)
 
-- **[ImageNet]** ImageNet Large Scale Visual Recognition Challenge | Olga Russakovsky, et al. | **[IJCV' 15]** | [`[pdf]`](https://arxiv.org/pdf/1409.0575.pdf)
+- **[ImageNet]** ImageNet Large Scale Visual Recognition Challenge | Olga Russakovsky, et al. | **[IJCV' 15]** | [`[pdf]`](https://arxiv.org/pdf/1409.0575.pdf) | [`[link]`](http://www.image-net.org/challenges/LSVRC/)
 
-- **[COCO]** Microsoft COCO: Common Objects in Context | Tsung-Yi Lin, et al. | **[ECCV' 14]** | [`[pdf]`](https://arxiv.org/pdf/1405.0312.pdf)
+- **[COCO]** Microsoft COCO: Common Objects in Context | Tsung-Yi Lin, et al. | **[ECCV' 14]** | [`[pdf]`](https://arxiv.org/pdf/1405.0312.pdf) | [`[link]`](http://cocodataset.org/)
 
-- **[Open Images]** The Open Images Dataset V4: Unified image classification, object detection, and visual relationship detection at scale | A Kuznetsova, et al. | **[arXiv' 18]** | [`[pdf]`](https://arxiv.org/pdf/1811.00982v1.pdf)
+- **[Open Images]** The Open Images Dataset V4: Unified image classification, object detection, and visual relationship detection at scale | A Kuznetsova, et al. | **[arXiv' 18]** | [`[pdf]`](https://arxiv.org/pdf/1811.00982v1.pdf) | [`[link]`](https://storage.googleapis.com/openimages/web/index.html)
 
 
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