What type of connection word is unless?

Explanation: A subordinate conjunction; you use it in conditional sentences

Hello!

Google Scholar is best used for a) scholarly resources, including articles and theses that span countless disciplines.

Why?

Google Scholar is a search engine especially designed for searching and indexing schorlarly and academic resources, like journals, books, technical reports, theses, conference papers and many more. It was launched in 2004. Google Scholar's slogan is "Standing on the shoulders of giants", a reference to the previous work of scientists and scholars, that is the foundation over which the new generations build upon.

Have a nice day!