How the world went from 170 million people to 7.3 billion, in one map - Vox
How the current world population reached 8 million... and what it means for Earth | Daily Mail Online
Demographics of the world - Wikipedia
How much more population can the Earth support? In 1930 (my birth year) there were about 2 billion inhabitants of our planet. Today, 90 years later, there are 7.8 billion humans. - Quora
How declining population growth might portend a future of increasing resource scarcity | CEPR