Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
lieu van » lieu va, hieu van, sieu van
sach ky » sac ky, sach y, sach ty
va hanh » van hanh, va thanh, va danh
ca tren » cau tren, la tren, co tren
cu tren » tu tren, dua tren
nam tu » nam thu, nam thuc
x hoi » xa hoi, o hoi, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky nang ((x hoi) OR (x ho)). lieu van nam tu va hanh vi ((ca tren) or (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((x hoi) OR (x ho)). lieu van nam tu va hanh vi ((ca tren) OR (cu tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang ((x hoi) OR (x ho)). lieu van nam tu va hanh vi ((ca tren) or (cu tren))".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ((x hoi) OR (x ho)). lieu van nam tu va hanh vi ((ca tren) or (cu tren))*.