Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
tuc van » thuc van, truc van, tuc va
cam tuc » cam xuc, cam tu, nam thuc
hieu va » lieu va, hieu qua
lang ha » long ha
ky lang » ky nang, ky dang, ky tang
va cam » va cham, va cac, va cao
ha hoi » hoa hoi, ha noi, xa hoi
cua tu » cua tuc, cua su, cua cu

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