Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
tu sach » su sach, te sach, tu cach
ty nang » ky nang, ty xang, ty hang
nang xa » nang x, lang xa, nang ma
cac duc » cac du, cao duc, cac dac
dau thi » cau thi, dan thi, dao thi
cuu tre » cau tren, cau treo
cua tre » cua te, cua triet, dua tren
va dau » va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (thu sach)) ty nang xa hoi. lieu va cac duc va dau thi ((cuu tre) OR (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ty nang xa hoi. lieu va cac duc va dau thi ((cuu tre) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) ty nang xa hoi. lieu va cac duc va dau thi ((cuu tre) OR (cua tre))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ty nang xa hoi. lieu va cac duc va dau thi ((cuu tre) OR (cua tre))*.