Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
cua viet » ca viet, hoa viet, cua vat
hieu va » lieu va, hieu qua
va tham » van tham, va cham, va thanh
y nang » ky nang, ly nang, v nang
xuc va » duc va, tuc va, xac va
luc va » duc va, tuc va, loc va
cua te » cua tu

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 y nang x ho. hieu va tham ((xuc va) OR (luc va)) hanh vi ((cua te) or (cua viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach y nang x ho. hieu va tham ((xuc va) OR (luc va)) hanh vi ((cua te) OR (cua viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach y nang x ho. hieu va tham ((xuc va) OR (luc va)) hanh vi ((cua te) or (cua viet))".
• Adding a wildcard symbol may retrieve word variants: doc sach y nang x ho. hieu va tham ((xuc va) OR (luc va)) hanh vi ((cua te) or (cua viet))*.