**[Shakir 16:43] And We did not send before you any but men to whom We sent revelation-- so ask the followers of the Reminder if you do not know **
Dhikr refers to the Quran, and it is also one of the names of the Holy Prophet. Ahl ul dhikr (the people of dhikr) are the Ahl ul Bayt (hadith al thaqalayn).
Dhikr literally means to call back to memory, or in other words to have something in conscious mind. It has been used figuratively for a stimulus which brings an object into the focus of consciousness. To be conscious of Allah, the Quran, the other scriptures and the Holy Prophet has been described as dhikr.
Some commentators hold that here dhikr refers to the previous scriptures and ahlul dhikr refers to the Jews and the Christians, but it is certainly a bad example of misinterpretation because even an ordinary teacher of Islamic ideology would not command a Muslim to refer to the Jewish and Christian scholars to remove his doubts, leave alone the all-wise Lord of the worlds. Dhikr means to be conscious of Allah and ahl refers to those who are always conscious of Allah as asserted in An Nur: 37.
Also dhikr means the Quran or the Holy Prophet and ahl refers to the people identified with the Holy Prophet and the Quran, thoroughly purified by Allah (Ahzab: 33) and are always with the Quran as per hadith al thaqalayn.