Sankhya Kārika
Karika 47
pañcaviparyayabhēdāḥ bhavantyaśaktēśca karaṇavaikalyāt। aṣṭāviṁśatibhēdā tuṣṭirnavadhāṣṭadhā siddhiḥ ॥47॥
Misunderstanding is of five types. Weakness due to impairment of instruments is of twenty-eight types. Complacency is of nine different types. Perfection is of eight types.
50 determinations = 5 misunderstandings (viparyaya) + 28 weaknesses (aśaktiḥ) + 9 complacencies (tuṣṭiḥ) + 8 perfections (siddhiḥ)]