Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
danh vai » danh sai, danh va, doanh van
va trien » va truyen, va tuyen, va tieng
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
hieu ve » hieu va, hieu van
ve pham » vi pham, v pham, ve phan
thuc va » thuc vat, thuc day
sach ky » sac ky, sach y, sach ty
thiet » thieu

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 lang xa hoi. hieu ve pham ((thuc va) OR (thuc dan)) danh vai ((va trien) or (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky lang xa hoi. hieu ve pham ((thuc va) OR (thuc dan)) danh vai ((va trien) OR (va thiet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ky lang xa hoi. hieu ve pham ((thuc va) OR (thuc dan)) danh vai ((va trien) or (va thiet))".
• Adding a wildcard symbol may retrieve word variants: doc sach ky lang xa hoi. hieu ve pham ((thuc va) OR (thuc dan)) danh vai ((va trien) or (va thiet))*.