Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
va danh » va dinh, va dan, va hanh
vai cua » hai cua, lai cua, bai cua
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, xa hoi, ma hoa
cac tu » cac thu, cach tu, cac du

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 ma hoi. hieu va cac tu va danh ((vai cua) or (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) y nang ma hoi. hieu va cac tu va danh ((vai cua) OR (dai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) y nang ma hoi. hieu va cac tu va danh ((vai cua) or (dai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) y nang ma hoi. hieu va cac tu va danh ((vai cua) or (dai cua)) tre*.