Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
vu sach » vu bach, su sach, vu khach
lang xa » lang ha, dang xay, lang van
hieu ve » hieu va, hieu van
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, dua tren
sach o » sach lo, sac o, sach y
o lang » hoa lang, hoi lang
ve cam » ve cham, ve cac, va cam

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 o lang xa hoi. hieu ve cam ((duc va) or (thuc vat)) hanh di ((cua tre) OR (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach o lang xa hoi. hieu ve cam ((duc va) OR (thuc vat)) hanh di ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach o lang xa hoi. hieu ve cam ((duc va) or (thuc vat)) hanh di ((cua tre) OR (cua triet))".
• Adding a wildcard symbol may retrieve word variants: vu sach o lang xa hoi. hieu ve cam ((duc va) or (thuc vat)) hanh di ((cua tre) OR (cua triet))*.