Assessing the effectiveness of greater occipital nerve block in chronic migraine: a systematic review and meta-analysis oleh Muhamad Saqlain Mustafa, Shafin bin Amin, Aashish Kumar, Muhammad Ashir Shafique, Syeda Mahrukh Fatima Zaidi, Syed Ali Arsal, Burhanudin Sohail Rangwala, Muhammad Faheem Iqbal, Adarsh Raja, Abdul Haseeb, Inshal Jawed, Khabab Abbasher Hussien Mohamed Ahmed, Syed Muhammad Sinaan Ali, Giustino Varrassi