Perhaps you should try some spelling variations:
manh thanh » danh thanh, minh thanh, manh thang
thanh tai » thanh hai, thanh toan, doanh tai
hieu van » hieu va, thien van, lieu va
dua tren » dung tren
van cao » van dao, van bao, van hao
su manh » suc manh, su menh, tu manh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
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: tu sach ky ((nang xa) OR (nang ma)) hoi. hieu van cao su manh thanh tai ((dua tren) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang ma)) hoi. hieu van cao su manh thanh tai ((dua tren) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang xa) OR (nang ma)) hoi. hieu van cao su manh thanh tai ((dua tren) or (cua te))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) OR (nang ma)) hoi. hieu van cao su manh thanh tai ((dua tren) or (cua te))*.