Air Companies to fly from Thailand to Cambodja and Myanmar?

I'm going to backpack to Cambodia this July, so I need some information before I go. Which air companies fly to Thailand for example, and from Thailand. I found one great site for booking flights for almost all air companies all over the world, but I dont know which company will take me to Cambodia. If you know how to find this info, post it please!

Following air line companies are flying to and from Cambodia and Myanmar: President Airlines, Royal Khmer Airlines Limited, Royal Phnom Penh Airways, Siem Reap Airways and Bangkok Airways. These are flying to Myanmar: Air Bagan Limited, Air Mandalay Limited, Air Mandalay, Myanmar Airways International Company Limited and Yangon Airways Limited. Those are flying to Thailand: Nok Air, Orient Thai Airlines, Phuket Airlines, Hua Hin Air Shuttle, and Thai Sky Airlines!