add cite for pose estimation

doc/START_POSE_ESTIMATION.md

@@ -4,9 +4,35 @@ We provide a demo for video-based pose estimation:
 ```shell
 mmskl pose_demo [--video $VIDEO_PATH] [--gpus $GPUS] [--$MORE_OPTIONS]
 ```
-This demo predict pose sequences via sequentially feeding frames into the image-based human detector and the pose estimator. By default, they are  **cascade-rcnn** and **hrnet** respectively. To check the full usage, please run `mmskl pose_demo -h`. You can also refer to [pose_demo.yaml](../configs/pose_estimation/hrnet/pose_demo.yaml) for detailed configurations.
+This demo predict pose sequences via sequentially feeding frames into the image-based human detector and the pose estimator. By default, they are  **cascade-rcnn** [1] and **hrnet** [2] respectively.
+We test our demo on 8 gpus of TITAN X and get a realtime speed (27.1fps). To check the full usage, please run `mmskl pose_demo -h`. You can also refer to [pose_demo.yaml](../configs/pose_estimation/hrnet/pose_demo.yaml) for detailed configurations. 
 
-We also provide another demo `pose_demo_HD` with a slower but more powerful detector. Similarly, run:
+We also provide another demo `pose_demo_HD` with a slower but more powerful detector **htc** [3]. Similarly, run:
 ```shell
 mmskl pose_demo_HD [--video $VIDEO_PATH] [--gpus $GPUS] [--$MORE_OPTIONS]
+```
+
+```
+@inproceedings{cai2018cascade,
+  title={Cascade r-cnn: Delving into high quality object detection},
+  author={Cai, Zhaowei and Vasconcelos, Nuno},
+  booktitle={Proceedings of the IEEE conference on computer vision and pattern recognition},
+  pages={6154--6162},
+  year={2018}
+}
+
+@article{sun2019deep,
+  title={Deep high-resolution representation learning for human pose estimation},
+  author={Sun, Ke and Xiao, Bin and Liu, Dong and Wang, Jingdong},
+  journal={arXiv preprint arXiv:1902.09212},
+  year={2019}
+}
+
+@inproceedings{chen2019hybrid,
+  title={Hybrid task cascade for instance segmentation},
+  author={Chen, Kai and Pang, Jiangmiao and Wang, Jiaqi and Xiong, Yu and Li, Xiaoxiao and Sun, Shuyang and Feng, Wansen and Liu, Ziwei and Shi, Jianping and Ouyang, Wanli and others},
+  booktitle={Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition},
+  pages={4974--4983},
+  year={2019}
+}
 ```