Where are most valid primary sources about texas state government history

This pie chart shows statistics related to the world's population. a pie chart like this one is most for making predictions about the future. showing how parts make up a whole. presenting amounts over a period of time. comparing information from different sources.

What battle in the civil war was known as the bloodiest war ?

The rise of advertising in the 1920s. i am good with seeing how advertisements shape the roaring twenties and how it developed a new way of life through modern days. but i am not sure what the details of advertising in the 1920s were. if possible can you send me links (preferrably credential links) to sources that maybe show like the first company to start advertising through the radio, how advertising benefits (statistics graphs), etc.