With educational materials increasingly varying in our modern lives, it is thought by many that not everything that is learned is contained in books. While, to a certain extent, this could be the case, I believe books are the most useful source of knowledge, because of the variety of books in content and format and reliability of knowledge in books.
Generally, there are several advantages of books associated with the variety in content and format, and reliability of knowledge in books. Considering the variety, books provide knowledge and information in different fields, ranging from science, society to economy. Books can be published in such formats as electronic, paper and spoken. It is convenient and easy for people to access the content of books in most conditions. Information in books has been verified carefully by publishing authorities. Thanks to this, knowledge and information in books has a high accuracy and could be a reliable source to study with.
Another advantage of books is the reliability of knowledge. All the knowledge in different kinds of books would be written by professional authors with extensive knowledge. A typical example of this is that textbooks learned by students at school provided them with exactly academic knowledge verified by an expert professor. Therefore, readers could completely trust in the information of books and learn it effectively.
In conclusion, I completely agree that books are the most useful source of knowledge because of the mentioned reasons. It is easy and effective to read and learn knowledge from books.