Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
pham duy » pham duc
hieu va » lieu va, hieu qua
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
va pham » van pham, va phat, va phap
tu lang » cu lang, tu lanh, xu lang
cuu tre » cua tre, cau tren, cau treo
duy va » duy vat, duy van, day va
di cuu » di cau, di cua, dinh cuu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) ((tu lang) OR (truc nano)) xa hoi. hieu va pham duy va hanh di cuu tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ((tu lang) OR (truc nano)) xa hoi. hieu va pham duy va hanh di cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ((tu lang) OR (truc nano)) xa hoi. hieu va pham duy va hanh di cuu tre*.