The law allows quotations to be made from copyright works, but only for criticism or review. This allows you to quote short extracts in an essay or dissertation. The limits are generally considered to be:
1. A single extract of no more than 400 words.
2. Several extracts totalling no more than 800 words, none more than 300 words.
3. 40 lines from a poem.
4. Proper acknowledgement must be made.