Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
hanh di » hanh de, hang di, danh di
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
sach v » sach va, sach y, sach 2
v lang » va lang, o lang, _ lang

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach v lang xa hoi. hieu va cac duc va ((hanh di) OR (hanh vi)) ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach v lang xa hoi. hieu va cac duc va ((hanh di) OR (hanh vi)) ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach v lang xa hoi. hieu va cac duc va ((hanh di) OR (hanh vi)) ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: doc sach v lang xa hoi. hieu va cac duc va ((hanh di) OR (hanh vi)) ((cua tre) or (cuu tre))*.