Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
cham luc » cham soc, nhan luc, cham cuu
van thai » van thoai, van tai, van hai
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
thai va » thai van
y nang » ky nang, ly nang, v nang
luc va » duc va, tuc va, loc va

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) or (thuoc sach)) y nang xa hoi. hieu van cham luc va van thai va (thiet* OR thieu*)~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thuoc sach)) y nang xa hoi. hieu van cham luc va van thai va (thiet* OR thieu*).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thuoc sach)) y nang xa hoi. hieu van cham luc va van thai va (thiet* OR thieu*)".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thuoc sach)) y nang xa hoi. hieu van cham luc va van thai va (thiet* OR thieu*)*.