Simplify the following text for a Grade 4 native English-speaking person.
Original: Vasa has been the subject of hundreds of books , articles and papers on topics ranging from marine archaeology to culinary history . Three children 's books about Vasa have been written in Swedish and later translated into English , German , Danish , and Norwegian : The Vasa Saga by Bertil Almqvist , The Vasa Sets Sail by Mats Wahl ( illustrated by Sven Nordqvist ) , and The Vasa Piglet by BjÃ rn Bergenholtz .
Simplified: Vasa was a big Swedish warship .