Many sources of company info will give you current information or data. Sometimes, they will provide a paragraph on the history of the company.
But if you want to know stuff like how GM was performing in 1945, you really need to look at specific reports dating from that period.
Aside from citing articles and books, have you ever wondered how to cite a company annual report or an industry report? The reality is, there is no "official" style for citing business sources. However, it is common practice to use adaptations of one of the following citation styles: the American Psychological Association (APA) Style or the Chicago Style. Whichever style you choose, use it consistently for the entire project/paper.