Q. How to cite with no date/unknown date.

According to the Online Writing Lab at Purdue University:

Unknown Author and Unknown Date: If no author or date is given, use the title in your signal phrase or the first word or two of the title in the parentheses and use the abbreviation "n.d." (for "no date").

Another study of students and research decisions discovered that students succeeded with tutoring ("Tutoring and APA," n.d.).