(2015). one step ahead: Towards environmental sustainability. united nation.
Čikaški stil citiranja (17. izdanje)One Step Ahead: Towards Environmental Sustainability. cairo: united nation, 2015.
MLA način citiranja (9. izdanje)One Step Ahead: Towards Environmental Sustainability. united nation, 2015.
Upozorenje: Ovi citati možda nisu uvijek 100% točni.