Perhaps you should try some spelling variations:
cam trung » cam truong, nam trung, cac trung
hanh vai » hanh vi, hanh va, hanh tai
trung va » truong va, trang va, trung ha
su sach » so sach, vu sach
ca viet » va viet, co viet, san viet
va hanh » van hanh, va thanh, va danh
qua cam » qua cham, qua cac, qua ca
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
sach v » sach va, sach y, sach 2

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 v ((nang xa) OR (nang ma)) hoi. hieu qua cam trung va hanh vai ((ca viet) or (hoa viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach v ((nang xa) OR (nang ma)) hoi. hieu qua cam trung va hanh vai ((ca viet) OR (hoa viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach v ((nang xa) OR (nang ma)) hoi. hieu qua cam trung va hanh vai ((ca viet) or (hoa viet))".
• Adding a wildcard symbol may retrieve word variants: su sach v ((nang xa) OR (nang ma)) hoi. hieu qua cam trung va hanh vai ((ca viet) or (hoa viet))*.