Perhaps you should try some spelling variations:
thien van » thi van
cua viet » ca viet, hoa viet, cua vat
van hanh » van thanh, ban hanh, van anh
truc van » truc va, thuc van, truc ban
lam truc » lam truoc, nam truc, lam thuoc
hieu van » hieu va, lieu va, hieu ve
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
vu sach » vu bach, su sach, vu khach
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach y ((nang xa) or (nang ma)) hoi. ((hieu van) OR (thien van)) lam truc van hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach y ((nang xa) OR (nang ma)) hoi. ((hieu van) OR (thien van)) lam truc van hanh vi cua viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach y ((nang xa) or (nang ma)) hoi. ((hieu van) OR (thien van)) lam truc van hanh vi cua viet*".