Perhaps you should try some spelling variations:
cham truc » cau truc, nham thuc, pham thuc
qua cham » qua hai, qua cac, va cham
truc van » truc va, thuc van, truc ban
van hanh » van thanh, ban hanh, van anh
hanh tai » thanh tai, hang tai, han tai
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
nang ro » nang co, nang ho, nang ra
nang va » nang van, hang va, nang ma
tai cua » thai cua, tai cuc, tri cua
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty ((nang ro) or (nang va)) hoi. hieu qua cham truc van hanh tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((nang ro) OR (nang va)) hoi. hieu qua cham truc van hanh tai cua te.
• Adding a wildcard symbol may retrieve word variants: su sach ty ((nang ro) or (nang va)) hoi. hieu qua cham truc van hanh tai cua te*.