Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hoi lang » hoa lang, hoi dan
hanh di » hanh de, hang di, danh di
cam loc » cam lo
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
loc va » hoc va, luc va
v lang » va lang, o lang, _ lang
va cam » va cham, va cac, va cao

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 ((v lang) or (hoi lang)) xa hoi. hieu va cam loc va ((hanh di) OR (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((v lang) OR (hoi lang)) xa hoi. hieu va cam loc va ((hanh di) OR (hanh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((v lang) or (hoi lang)) xa hoi. hieu va cam loc va ((hanh di) OR (hanh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((v lang) or (hoi lang)) xa hoi. hieu va cam loc va ((hanh di) OR (hanh vi)) cua tre*.