Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va gianh » va gian, van giang, va giai
sach ky » sac ky, sach y, sach ty
ky sang » ky nang, ky dang, ky tang
hieu ve » hieu va, hieu van
duoc va » nuoc va, duc va, duoc ma
lai cua » hai cua, lai chau, thai cua
me hoi » le hoi
ve tao » ve bao, de tao, ve tac

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky sang ((me hoi) or (ma hoa)). hieu ve tao duoc va gianh ((lai cua) or (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky sang ((me hoi) OR (ma hoa)). hieu ve tao duoc va gianh ((lai cua) OR (dai cua)) tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ky sang ((me hoi) or (ma hoa)). hieu ve tao duoc va gianh ((lai cua) or (dai cua)) tre*.