Research on any topic may involve the use of primary and secondary sources. Primary sources provide a first-hand account or the raw, un-interpreted information. Secondary sources provide an interpretation or review of the information. Here are some examples of sources you could find for the topic of "Standing Rock and NoDAP."
Encyclopedias or Dictionaries
Many of these databases can help in finding scientific research as it relates to the topic of the environment and trash, waste, and garbage.