Here are two helpful Internet sources I came across in my research for Psalm 110. They are clear and good summaries.
A messianic Jewish article explaining the meaning of Psalm 110.
An article about Jesus’s identity – what did Jesus think about the Messiah being the son of David?
Both of these are short and take into account important things related to seeing Psalm 110 in a Jewish/Hebrew perspective in order to see it properly in reference to its fulfillment in Christ.