you put ther author of the book and then the page number on which you found the information that your writing about in parentheses in the sentence, for example:Stars are made up of gas, ice, and dust...
In general, until it decomposes or gets destroyed, which would be a long, long time. In schools, only about 5-10 years, as books are always getting updated.
In a text book there is the main title and then maybe a paragraph and then there is another title. that is the subtitle. there will be a few paragraphs in that and then another subtitle. the subtitle...