Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
va thanh » gia thanh, ban thanh, va tinh
ky sang » ky nang, ky tang, duy sang
ky dang » ky nang, ky danh
tao hoi » tao khoi, tao boi, tay hoi
ve pham » v pham, ve phan, ve phat
san cua » sang cua, ban cua, dan cua
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 ((ky sang) or (ky dang)) tao hoi. hieu ((ve pham) OR (vi pham)) duc va thanh san cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ((ky sang) OR (ky dang)) tao hoi. hieu ((ve pham) OR (vi pham)) duc va thanh san cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ((ky sang) or (ky dang)) tao hoi. hieu ((ve pham) OR (vi pham)) duc va thanh san cua te".
• Adding a wildcard symbol may retrieve word variants: doc sach ((ky sang) or (ky dang)) tao hoi. hieu ((ve pham) OR (vi pham)) duc va thanh san cua te*.