There are 19 Upanishads which belong to Sukla Yajur Veda.
List of Upanishads which pertain to Sukla Yajur Veda:
1. Adhyatma Upanishad
2. Advaya-Taraka Upanishad
3. Bhikshuka Upanishad
4. Brihadaranyaka Upanishad
5. Hamsa Upanishad
6. Isavasya Upanishad
7. Jabala Upanishad
8. Mandala-Brahmana Upanishad
9. Mantrika Upanishad
10. Muktika Upanishad
11. Niralamba Upanishad
12. Paingala Upanishad
13. Paramahamsa Upanishad
14. Satyayaniya Upanishad
15. Subala Upanishad
16. Tara-Sara Upanishad
17. Trisikhi-Brahmana Upanishad
18. Turiyatita-Avadhuta Upanishad
19. Yajnavalkya Upanishad