Original sentence: To date, the available pretreatment techniques include acid hydrolysis, steam explosion, ammonia fiber expansion, organosolve, sulfite pretreatmet to overcome recalcitrance of lignocellulsoe (SPORL) , alkaline wet oxidation and ozone pretreatment
Edited sentence: To date, the available pretreatment techniques include acid hydrolysis, steam explosion, ammonia fiber expansion, organosolve, sulfite pretreatmet to overcome recalcitrance of lignocellulsoe (SPORL) <ref> , alkaline wet oxidation and ozone pretreatment