In most disciplines, there is a core database that indexes the scholarly literature in that field. Here are some examples:

If you want to search across a range of disciplines, then you'll want to use these databases:

Wouldn't you like a free piece of software that:

• will save all the publication info about an article or book with a single mouse click?
• let you backup your collection of citation across multiple computers
• generate properly formatted citations as you write

Recommendation: use the free Zotero software.