Perhaps you should try some spelling variations:
sach hoi » sach doi, sach moi, cach thoi
hanh da » hanh dao, hanh dua, hanh va
sach ly » sach y, sach lo, sach ty
hieu va » lieu va, hieu qua
tang ma » mang may, tang van
cu tren » tu tren, dua tren
ma hoi » mai hoi, xa hoi, ma hoa
va lam » van lam, va lap
loc va » luc va
da cu » da cau, dan cu, da cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ly) or (sach hoi)) tang ma hoi. hieu va lam ((loc va) OR (hoc va)) hanh da cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ly) OR (sach hoi)) tang ma hoi. hieu va lam ((loc va) OR (hoc va)) hanh da cu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ly) or (sach hoi)) tang ma hoi. hieu va lam ((loc va) OR (hoc va)) hanh da cu tren".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ly) or (sach hoi)) tang ma hoi. hieu va lam ((loc va) OR (hoc va)) hanh da cu tren*.