Use either JSTOR or Google Scholar to research contemporary scholarship related to Kennedy's tax policy. Limit the date range to 1961-1966. With JSTOR, limit your subject to "Economics." Don't focus on what has been written 20 to 50 years after Kennedy's policy.
The best way to approach newspaper articles contemporary to pivotal moments related to Kennedy's tax policy is to identify a significant event (e.g State of the Union Address of 1963, Yale Commencement Speech of 1962, or the 1964 signing of the Revenue Act) and search one of the historic newspaper archives below, limiting your dates to the week immediately following the event.