No reference here but found this out the hard way too. Google search Ali is Utterly useless in fact and entirely different search results vs using the web. Bing is better. Haven’t tried ksgi yet

"References"? :-) This is a corporation we're talking about, and Google at that. Layers upon layers of obscurity, "strategic decisions" and discontinued products.

Try it and you'll see — there is no official Search API and the Custom Search API is quite poor and not usable in most scenarios.