The third book in Spanish is "el tercer libro." If you're referring to a specific book, you might say "el tercer libro de [title]." The word "tercer" is the masculine form of "third," used for masculine nouns like "libro."
We say lower third in spanish like this-el tercio inferior.
la mochila is how you say book bag in spanish
Libro de texto(Literally "book of text")
you say it `este libro'.
libro
Tercer cuarto
Tres hora
Tercer Imperio
"on the book" "en el Libro"
El Libro= The book Libros= Books
cuaderno
nuestro libro