Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
hanh tai » thanh tai, hang tai, han tai
doc sach » hoc sach, nuoc sach, dac sac
va hanh » van hanh, va thanh, va danh
cam tuc » cam xuc, cam tu, nam thuc
hieu va » lieu va, hieu qua
tang ma » mang may, tang van
tang xa » trang xa, lang xa, tang ha
va cam » va cham, va cac, va cao
tuc va » thuc va, truc va, tuc xa
cuc te » cua te, cuc thue, cuc tieu

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) or (doc sach)) ky ((tang xa) or (tang ma)) hoi. hieu va cam tuc va hanh tai cuc te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ky ((tang xa) OR (tang ma)) hoi. hieu va cam tuc va hanh tai cuc te.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) ky ((tang xa) or (tang ma)) hoi. hieu va cam tuc va hanh tai cuc te*.