What is proof of income in an education loan?

Here is the list of financial documents required to apply for the loan:

For Salaried Applicants or Co-applicants

• Salary slips (last 3–6 months)
• Bank statements (last 6–12 months)
• Income Tax Returns (ITR) or Form 16 (last 2–3 years)
• Employment verification letter

For Self Employed Applicants or Co-applican