Ecosystems:The structure of the ecosystems. Ecosystems. BILINGUAL UNITS.

https://docs.google.com/file/d/0BzRJteJjM7m_ZWQ4NzM1OGItZWIxZC00ZjI4LTk2YzgtZWM5OWZmOGYzMTM5/edit?hl=en

https://docs.google.com/file/d/0BzRJteJjM7m_MGNkNWQ0ZWItZjY4MS00NjlhLThiN2EtODA4NDQ5YzJjZTc0/edit?hl=en