Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
trung va » truong va, trang va, trung ha
van hac » van hoc, van ha, van hai
xanh di » danh di, vanh dai, xanh tai
va xanh » va danh, va hanh, va anh
van bac » van ban, van bao, dan bac
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
y nang » ky nang, ly nang, v nang
di cua » dai cua, doi cua, de cua

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