Perhaps you should try some spelling variations:
tinh doi » trinh doc, trinh do, tinh hoc
cu tren » tu tren, dua tren
cam duc » cam xuc, pham duc, nam duoc
nang ma » tang ma, nang cao, mang may
sang ma » tang ma, sang tao, mang may
va tinh » may tinh
hieu va » lieu va, hieu qua
cao duc » dao duc, cao suc, giao duc
doi cu » doi cua, doi co, doi ca
tu san » thu san, tu ban, tu can
san ky » sang ky, van ky, dan ky

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

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