Leave no stone unturned.

Google Scholar may be.

Science direct

firstly you should use google , which guide you to the more specific site

I usually use Google.

Mathematical Reviews and Zentralblatt für matematikk for mathematics plus Web of Knowledge, Science Direct, Springer, Google Scolar for search in all disciplines Including mathematics.

I use Google Scholar:

https://scholar.google.com.ua

It finds article, articles that cite article that I found interested and so on.

Google Scholar is better for academic research than Google. Instead of searching for needles in the proverbial haystack, it puts you in the needlestack, so to speak. Nevertheless, sometimes useful information will turn up on a Google search and not with Google Scholar, so I still stand by my comment of a week ago ("Leave no stone unturned").