Some professional nursing organizations with relevant position papers or 'white' papers may include the Association of Psychiatric Nurses Association, https://www.apna.org, the International Society of Psychiatric-Mental Health Nurses, https://www.ispn-psych.org/, and the American Nurses Association, https://www.nursingworld.org/.
The easiest way to find these papers is to conduct a Google search, limiting the results to the organization's website URL. For example, copying and pasting the following bolded text into the Google search box below yields some relevant results.
position paper seclusion or restraint site:apna.org
Modify your search, using alternate terms or URLs to find other/different results.