Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
va nhan » van nhan, ca nhan, va phan
duc ban » duc tan, dua ban, duc man
duc van » duc va, duc tan, duc manh
doi cua » dai cua, hoi cua
do cua » co cua, de cua, dong cua

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 ky nang xa hoi. hieu va nhan ((duc ban) OR (duc van)) thanh ((do cua) or (doi cua)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky nang xa hoi. hieu va nhan ((duc ban) OR (duc van)) thanh ((do cua) OR (doi cua)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ky nang xa hoi. hieu va nhan ((duc ban) OR (duc van)) thanh ((do cua) or (doi cua)) te".
• Adding a wildcard symbol may retrieve word variants: doc sach ky nang xa hoi. hieu va nhan ((duc ban) OR (duc van)) thanh ((do cua) or (doi cua)) te*.