Please recommend textbooks for preparing for TOPIK II.

I am looking for suitable study materials while preparing for the TOPIK II exam. I am confident in my Korean speaking skills, but I still feel lacking in reading, writing, and listening. I recently scored level 3 on a TOPIK II mock exam. I would especially like recommendations for good materials or resources to improve my reading and writing skills. If anyone knows of study groups or materials available around Gangnam or Hongdae, I would appreciate your advice. I am looking forward to your experiences or recommendations. This will greatly help me advance my language skills to the next level. Thank you.