Sakamakon bincike

...ashi . Kuma Wasu matakai na iskar gas suna da niyya don tace abubuwan toka masu lalata kamar su chloride da potassium, ba da damar samar da iskar gas mai t ...aga shekarun 1920. Dubban shafuka sun bar ragowar masu guba. An gyara wasu shafuka, yayin da wasu kuma har yanzu gurɓatacce ne.<ref>{{cite web |title=A centur ...