Furfuraldehyde???

I am confused and do not know where I can find literature that describes the relationship btween furan, CO, CO2 with the maintenance which apply to the transformers oil. iI need it to complete my mini thesis in the university. I hope someone can explain to me about it, as for the question unanswered till today is:
whether the content of furfuraldehyde in the transformer is affected by the maintenance performed on transformer oil?
What kind of maintenance can reduce furfuraldhyde content in transformer oil?
What maintenance can reduce the content of CO and CO2 gases in transformer oil?
whether furification intended to reduce the water content, can also cause a reduction in CO and CO2 content of gas in transformer oil?