Perhaps you should try some spelling variations:
hanh doi » thanh doi, hanh noi, hang doi
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
cac tuc » cac tu, cac tac, cac nuoc
cac toc » cac toi, cac nuoc, cac thoi
va hanh » van hanh, va thanh, va danh
ca tren » cau tren, cu tren, la tren
doi ca » doi cua, doi cay, duoi ca
5 hoi » o hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky nang ((5 hoi) or (x ho)). hieu qua ((cac tuc) OR (cac toc)) va hanh doi ca tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((5 hoi) OR (x ho)). hieu qua ((cac tuc) OR (cac toc)) va hanh doi ca tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((5 hoi) or (x ho)). hieu qua ((cac tuc) OR (cac toc)) va hanh doi ca tren*".