APA (7th ed.) Citation

Sitorus, L. (2004). WINDOW ON THE WORLD English for SMA Year 1. Erlangga.

Chicago Style (17th ed.) Citation

Sitorus, Lungguk. WINDOW ON THE WORLD English for SMA Year 1. Erlangga, 2004.

MLA (8th ed.) Citation

Sitorus, Lungguk. WINDOW ON THE WORLD English for SMA Year 1. Erlangga, 2004.

Warning: These citations may not always be 100% accurate.