Perhaps you should try some spelling variations:
khong thuoc » khang thuoc, hong phuoc, dong thuoc
pham khong » pham hong, pham thuong, pham chuong
thuoc dai » thuoc tai, thuoc dac, thuoc sai
sach hoc » cach hoc, sach hoi, mach hoc
cuu dong » cuu cong, cuu tong, cuu long
dong hoc » dong co, dong luc
hoc pham » hoc phan, hoc phat, hoc phap
nhan dan » phan dau, gian dan, nhan tai
te sach » toc sach
choi va » hoi va, chai va, cho va
khi va » phi va

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach hoc tap, nghien cuu dong hoc pham khong thuoc dai ((choi va) or (khi va)) nhan dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach hoc tap, nghien cuu dong hoc pham khong thuoc dai ((choi va) OR (khi va)) nhan dan.
• Adding a wildcard symbol may retrieve word variants: te sach hoc tap, nghien cuu dong hoc pham khong thuoc dai ((choi va) or (khi va)) nhan dan*.