Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
hanh tai » thanh tai, hang tai, han tai
tai cua » thai cua, tai cuc, tri cua
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
va cam » va cham, va cac, va cao
tuc va » thuc va, truc va, duc va
cua tu » cua tuc, cua su, cua cu

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

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