Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach thi » sach thu, sach tai, sach thieu
thi nang » thi cong, ki nang, thi hanh
hanh tai » thanh tai, hang tai, han tai
hanh lai » hanh lam, thanh lap, thanh loi
cac thuc » cach thuc, can thuc, cay thuc
cac thu » cach thuc, cac thoi
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
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: toc sach thi nang ma hoi. hieu va ((cac thuc) or (cac thu)) va ((hanh lai) OR (hanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach thi nang ma hoi. hieu va ((cac thuc) OR (cac thu)) va ((hanh lai) OR (hanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach thi nang ma hoi. hieu va ((cac thuc) or (cac thu)) va ((hanh lai) OR (hanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach thi nang ma hoi. hieu va ((cac thuc) or (cac thu)) va ((hanh lai) OR (hanh tai)) cua tre*.