Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
tinh hai » tinh thai, tinh chat, trinh han
tinh bai » tinh bac, hinh bai, tinh bao
nhan luc » nang luc
hieu de » hieu ve, hieu he, hieu le
de nhan » do nhan, tue nhan, de thanh
xay hoi » tay hoi, cay phoi, gay thoi
y dang » ky dang, 2 dang, _ dang
luc va » duc va, tuc va, loc va
ca tre » ca tren, cua tre, ca tru

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc sach y dang ((xay hoi) OR (xa hoi)). hieu de nhan luc va ((tinh bai) or (tinh hai)) ca tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach y dang ((xay hoi) OR (xa hoi)). hieu de nhan luc va ((tinh bai) OR (tinh hai)) ca tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach y dang ((xay hoi) OR (xa hoi)). hieu de nhan luc va ((tinh bai) or (tinh hai)) ca tre".
• Adding a wildcard symbol may retrieve word variants: thuoc sach y dang ((xay hoi) OR (xa hoi)). hieu de nhan luc va ((tinh bai) or (tinh hai)) ca tre*.