How to say thanks?

[Diamondsmith]

How to express thanks to your friends who have help you in your writing? I saw some expressions like "I would like to thank Dr John Smith for his valuable help in organizing the structure of the research...But all error would be my responsibility..blabla", but I forgot the exact words and phrases. How to express this properly? How many ways are there to express such meanings?

[Aalizzwell]

Just say it from the heart. Showing them you really appreciate their effort of helping you is enough. Though giving letters or presents make the scene touching.:) yet, it still depends on how you deliver your appreciation.

[Sean_Vn]

The mosquitoes are biting my legs this evening in Hanoi. I can't thank you enough for reading this. I am so grateful. How wonderfully kind of you.