Katigbak, A. F. (2003). Almost 80 percent of Pfizer's sildenafil users prefer not to take other ED medications. Philippine Star.
芝加哥风格引文Katigbak, Antonio F. "Almost 80 Percent of Pfizer's Sildenafil Users Prefer Not to Take Other ED Medications." Philippine Star 2003.
MLA引文Katigbak, Antonio F. "Almost 80 Percent of Pfizer's Sildenafil Users Prefer Not to Take Other ED Medications." Philippine Star, 2003.
警告：这些引文格式不一定是100％准确.