How to get notified when a specific paper is cited I cannot find anymore the option to get notified with an alert on google scholar when a specific paper gets cited. 

I am sure I could set up this a while ago because if I go in my profile I can see that an alert like this is there and it is still active. 

Did google remove this option or I just cannot find it anymore? 

Thanks for your help.
If you asking this for your paper(s), then this is procedure:
Go to your Google Scholar profile, and click on some paper/article title. Now you will have one new window open, in which you have to click on the "Cited by" link at the bottom left of that window. Finally, you want to click on the envelope icon in the left sidebar to create alert... The similar procedure will work on papers from other authors!