Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
van hanh » van thanh, ban hanh, van anh
vien cac » vien bach, vien dai, vien da
ty nang » ky nang, ty xang, ty hang
nang xa » nang x, lang xa, nang ma
sach ty » sach y, sach tu, sach thu
duc van » duc va, duc tan, duc manh
cua cu » cua chu, cua cau, cua co
ve cac » va cac
cua su » qua su

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