Perhaps you should try some spelling variations:
cach thoi » cac thoi, cach thuc, cach noi
cua viet » ca viet, hoa viet, cua vat
nang mai » nang ma, nang tai, lang mai
mai khoi » mai khoa, tai khoa, cac khoi
sach hoi » sach doi, sach moi, hoach hoi
hieu va » hieu qua
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
thu va » thuc va, thue va, tu va
di cua » dai cua, doi cua, de cua

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 hoi) or (cach thoi)) nang mai khoi. ((lieu va) or (hieu va)) nam thu va hanh di cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach hoi) OR (cach thoi)) nang mai khoi. ((lieu va) OR (hieu va)) nam thu va hanh di cua viet.
• Adding a wildcard symbol may retrieve word variants: su ((sach hoi) or (cach thoi)) nang mai khoi. ((lieu va) or (hieu va)) nam thu va hanh di cua viet*.