We recommend that you try to import sources to your library from databases and web pages when this is possible. Manually adding a source should be last resort. Imported references are quality checked with less risk for spelling errors and similar which may occur when you add a source manually. Generally, some sources have to be added manually and it is important that you ensure the quality of the data you add. NTNU Academic Writing can provide information about how to manually add many different types of sources.
It is important to remember that quality input creates quality output. EndNote cannot generate correct citations and reference lists if there are errors or lack of data in the library references.