who should I obtain letters from?

[dollar500]

I was wondering if somebody whom can I get letters from. i have the following options.
1. Mentor,
2. People I have worked with in past.
3. One acquainatence

Who else can i ask? I was also told that i should get letters from people I have never worked with. How would somebody approach somebody randomly? I am going to a national meeting next month and hopefully meeting a few people, how to approach them?

Thanks in advance?

 

[limmigrant2]

1) Supervisor and Top directors of your company/lab.
2) Top experts who know you personally and worked with you.
3) Top experts who have not been employed at the same place as you but met you at conferences, committees, email exchanges etc.
4) Top experts who are familiar with your work and never met you.

 

[limmigrant2]

1) Supervisor and Top directors of your company/lab.
2) Top experts who know you personally and worked with you.
3) Top experts who have not been employed at the same place as you but met you at conferences, committees, email exchanges etc.
4) Top experts who are familiar with your work and never met you.

 

[mhush]

in my case, i went with five individuals that knew me and three individuals that did not know me but could judge me based on my CV. i've heard that this is important to show the strength of your application.