More recently items of recent media interest or advertisements form a key theme.

A key theme within the play is the right of life.

Fine, except for one point and a key theme of this book: walls.

As with the principles above, there is no official list of key themes.

Listed below are seven key themes to focus the work of our agency.

Another key theme throughout the book is the relationship between Waltz and his parents.

Apart from politics, a key theme in Lowe's play is work itself.

Employment should be, and is, the key theme of the three reports before us this morning.

In its defense, Microsoft has leaned on two key themes.

A key theme of their work is the relationship between language and space.