Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thuc van » thuc vat, thuc dan, thuc va
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
vuc van » duc van, luc van, chuc van
y nang » ky nang, ly nang, v nang
ve cam » ve cham, ve cac, va cam
cua tu » cua tuc, cua su, cua te
cua cu » cua chu, cua cau, cua su

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 y nang xa hoi. hieu ve cam ((vuc van) OR (thuc van)) hanh vi ((cua tu) or (cua cu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang xa hoi. hieu ve cam ((vuc van) OR (thuc van)) hanh vi ((cua tu) OR (cua cu)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y nang xa hoi. hieu ve cam ((vuc van) OR (thuc van)) hanh vi ((cua tu) or (cua cu))".
• Adding a wildcard symbol may retrieve word variants: toc sach y nang xa hoi. hieu ve cam ((vuc van) OR (thuc van)) hanh vi ((cua tu) or (cua cu))*.