Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
cau tren » cu tren, ca tren, cau treo
dong hoa » dong hoc, dong co
hieu van » hieu va, thien van, lieu va
sach sy » sach y, sach ty, sach hay
hanh va » hang va, hanh vi
tu sach » thu sach, su sach, te sach
van lam » van nam
hoa hoi » khoa hoi, hoa hoc, hoa doi
sy dong » ly dong, so dong, su dong
tuc va » thuc va, truc va, tuc xa
xuc va » duc va, luc va, xac va

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 sy dong hoa hoi. hieu van lam ((xuc va) or (tuc va)) hanh va ((cau tren) OR (dau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach sy dong hoa hoi. hieu van lam ((xuc va) OR (tuc va)) hanh va ((cau tren) OR (dau tren))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach sy dong hoa hoi. hieu van lam ((xuc va) or (tuc va)) hanh va ((cau tren) OR (dau tren))*".