Academic search results
It seems that for some searches on Microsoft academic API (and Microsoft's own web portal), the top result (in terms of relevance and citations count) is absent.
For example, search for "topological insulators". The top result, correctly given by Google scholar, is the most cited review article in the field, from 2010 (7454 citations), titled Colloquium: topological insulators.
In Microsoft's academic however, there is no mention of this seminal article no matter if you order results by relevance or by citations.
How can that be?