Simplify the following text for a Grade 12 native English-speaking person.
Original: Individual songs from some of the operettas have become standards , notably `` Vilja '' from The Merry Widow and `` You Are My Heart 's Delight '' ( `` Dein ist mein ganzes Herz '' ) from The Land of Smiles ( Das Land des LÃ chelns ) .
Simplified: Some of the songs from his operettas have become very well-known , especially `` Vilja '' from The Merry Widow and `` You Are My Heart 's Delight '' ( `` Dein ist mein ganzes Herz '' ) from The Land of Smiles .