Perhaps you should try some spelling variations:
khang thuoc » dang thuoc, hanh thuoc, khau thuoc
khong thuoc » hong phuoc, dong thuoc, khoa thuoc
hoc nhanh » hoc nganh, hoc phan
sach hoc » cach hoc, sach hoi, mach hoc
cuu dong » cuu cong, cuu tong, cuu long
dong hoc » dong co, dong luc
khoi bay » khi bai, hoi bai
bay phap » ban phap, tay phap, va phap
phap vat » phap luat, phap phat, phap viet
tu sach » thu sach, su sach, te sach
va khoi » van khoi, va hoi, va khi

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach hoc tap, nghien cuu dong hoc nhanh ((khang thuoc) or (khong thuoc)) va khoi bay phap vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoc tap, nghien cuu dong hoc nhanh ((khang thuoc) OR (khong thuoc)) va khoi bay phap vat.
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu dong hoc nhanh ((khang thuoc) or (khong thuoc)) va khoi bay phap vat*.