Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
dan dai » dat dai, can dai, dan dat
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
ve tai » te tai, de tai, le tai
va cam » va cham, va cac, va cao
va dan » ca dan, va dao, va dau
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)) ty nang xa hoi. hieu ((ve tai) or (va cam)) duc va dan dai cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ty nang xa hoi. hieu ((ve tai) OR (va cam)) duc va dan dai cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) ty nang xa hoi. hieu ((ve tai) or (va cam)) duc va dan dai cua tu".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) ty nang xa hoi. hieu ((ve tai) or (va cam)) duc va dan dai cua tu*.