I am researching the Balkan's involvement in World War 1. Specifically, Bulgaria, Serbia, and Romania.

**My question is:**

What were Romanian - and Bulgarian relations in, and around the lead-up to the First World War, and the War itself. And, what were the relations of the Great European Powers, and the Balkans within 1900 - 1920 (why did they consider the Balkans valuable, and what did they do about it).