How to correctly know the “official” Twitter handles of politicians or celebrities?
Here is the page which you are looking for: http://indiancelebsontwitter.com/ It contains some big politicians and all Bollywood celebrities. All are the true accounts of the people. Note that not all politicians or celebrities have a twitter account. Even if you are searching for someone's twitter account he/she may or may not have one.
Also, if you go to their 'Official' webpage, there will be a link to their 'Official' Twitter page right on it.
Can you pl mention link of twitter handle of "Lal Krishna Advani" ?
As Vipul said you can identify twitter handles via the blue check mark.
There is no way of telling whether those verified accounts are used by the politician or celebrity themselves or by some PR department. In the same way if they do have other "private" accounts there is no easy way of finding them unless they were leaked in some way.
Search them by their name.
The ones with a Blue tick in front of their twitter handle are the real & verified ones.
Yes thats correct