| Criteria | Required | Red Flag | | :--- | :--- | :--- | | | Within 2 years | Older than 4 years | | Referenced Standards | ISO 5817:2023, ASME IX 2023 | ISO 5817:2006 | | Worked Calculations | Minimum 20 examples | None or only formula lists | | Mock Exams | Minimum 3 full papers | No mock exams | | Author Credentials | CSWIP 3.2 or TWI tutor | Anonymous or "student notes" |