Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
cau tren » cu tren, ca tren, cau treo
va tinh » may tinh
nang ma » tang ma, sang ma, nang cao
tinh di » tinh doi, trinh di, tinh da
va cham » va chat, va tham
tu san » thu san, tu ban, tu can
san ky » sang ky, van ky, dan ky
va cam » va cac, va cao, va cai
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu san ky nang ma hoi. hieu ((va cam) OR (va cham)) duc va tinh di ((cau tren) or (dau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu san ky nang ma hoi. hieu ((va cam) OR (va cham)) duc va tinh di ((cau tren) OR (dau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu san ky nang ma hoi. hieu ((va cam) OR (va cham)) duc va tinh di ((cau tren) or (dau tren))".
• Adding a wildcard symbol may retrieve word variants: tu san ky nang ma hoi. hieu ((va cam) OR (va cham)) duc va tinh di ((cau tren) or (dau tren))*.