Britannica Educational Publishing 
Closer Look at Biology, Microbiology, and the Cell [PDF ebook] 

Formalizing study of the natural world may seem like a daunting task considering the sheer breadth and variety of living things that inhabit the planet. From the microscopic organisms in the world’s most remote locations to those in the human body, evidence of the intricate structures and mechanisms that enable life are ubiquitous and new discoveries constantly reveal new possibilities that demand to be examined. This volume surveys the multitude of subjects that comprise the field of biology and includes an overview of the development of biology, microbiology, and cell theory.