You can use the following links to learn more:

• If you are interested in the paper that introduced the Deterministic Policy Gradient (DPG) algorithm, read: http://proceedings.mlr.press/v32/silver14.pdf.
• If you are interested in the paper that introduced the Deep Deterministic Policy Gradient (DDPG) algorithm, read: https://arxiv.org/pdf/1509.02971.pdf.
• The paper that presented Twin Delayed Deep Deterministic Policy Gradient (TD3) can be found here: https://arxiv.org/pdf/1802.09477.pdf
• For a brief overview of all the main policy gradient algorithms, checkout this article by Lilian Weng: https://lilianweng.github.io/lil-log/2018/04/08/policy-gradient-algorithms.html.