Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
thu nang » thi nang, thu hang, tho nang
hanh vai » hanh vi, hanh va, hanh tai
thu bang » thu ban, thu hang, chu bang
vai cuu » vai cua
cuu tre » cua tre, cau tren, cau treo
hieu va » lieu va, hieu qua
tuc va » thuc va, truc va, duc va
va cam » va cham, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ((thu nang) or (thu bang)) xa hoi. hieu va cam ((tuc va) OR (tuc xa)) hanh vai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ((thu nang) OR (thu bang)) xa hoi. hieu va cam ((tuc va) OR (tuc xa)) hanh vai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ((thu nang) or (thu bang)) xa hoi. hieu va cam ((tuc va) OR (tuc xa)) hanh vai cuu tre".
• Adding a wildcard symbol may retrieve word variants: doc sach ((thu nang) or (thu bang)) xa hoi. hieu va cam ((tuc va) OR (tuc xa)) hanh vai cuu tre*.