Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
kham duc » pham duc, kham cuoc, pham duy
dau cua » dai cua, day cua, cau cua
dan dau » danh dau, doan dau, van dau
va kham » va cham, va khao, va tham
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
v nang » va nang, vu nang, van nang
va dan » ca dan, va dao, va dau
y nang » ky nang, ly nang, may nang
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: ((te sach) OR (toc sach)) ((y nang) or (v nang)) ma hoi. hieu va kham duc va dan dau cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ((y nang) OR (v nang)) ma hoi. hieu va kham duc va dan dau cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ((y nang) or (v nang)) ma hoi. hieu va kham duc va dan dau cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ((y nang) or (v nang)) ma hoi. hieu va kham duc va dan dau cua tre*.