Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
tinh di » tinh doi, trinh di, tinh da
thuc va » thuc vat, thuc dan, thuc day
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
tuc va » truc va, tuc xa, duc va
di cua » dai cua, doi cua, de cua
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ty nang x hoi. ((hieu ve) or (hieu qua)) cau ((tuc va) OR (thuc va)) tinh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang x hoi. ((hieu ve) OR (hieu qua)) cau ((tuc va) OR (thuc va)) tinh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang x hoi. ((hieu ve) or (hieu qua)) cau ((tuc va) OR (thuc va)) tinh di cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang x hoi. ((hieu ve) or (hieu qua)) cau ((tuc va) OR (thuc va)) tinh di cua tre*.