Perhaps you should try some spelling variations:
cam thue » cam thu, lam thue, nam thue
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
thue va » thuc va, thuyet va, thuc vat
va hanh » van hanh, va thanh, va danh
hai cua » thai cua, hoi cua, lai cua
tu can » tu ban, tu cac, thu canh
can ky » van ky, dan ky, ban ky
va cam » va cham, va cac, va cao

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu can ky ((nang x) or (nang ma)) hoi. hieu va cam thue va hanh ((hai cua) or (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu can ky ((nang x) OR (nang ma)) hoi. hieu va cam thue va hanh ((hai cua) OR (dai cua)) tre.
• Adding a wildcard symbol may retrieve word variants: tu can ky ((nang x) or (nang ma)) hoi. hieu va cam thue va hanh ((hai cua) or (dai cua)) tre*.