Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh may » hanh ma, hanh mau, hanh ngay
may duc » mai duc, my duc
va hanh » van hanh, va thanh, va danh
cac tuc » cac toc, cac tu, cac tac
hieu va » lieu va, hieu qua
ky danh » ky anh
ky dang » ky nang
duc tre » duoc tren, duc tien
tuc va » thuc va, truc va, tuc xa

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