This is a common issue that has been faced by us once or more in our college and school time. The appropriate resolution for this differs as to which university or organization one studies in. Still, the below solutions could help.
1. If carrying a mobile phone is allowed in your library, click a picture of the important topics you wished to study from the book you want to get issued.
2. You may also get these books issued on the card of any other student. We used to have the books issued through identity cards in our school and college. In case of a dire emergency, I used to ask my friends to get my book issued on their card. This will help you a lot.
3. You can also request your librarian to re-issue the book for another week. The same book will, therefore, remain with you for another fortnight or another week then.
4. Usually, libraries have an adjacent stationery shop or some system of getting the photocopies done. So, in this case, you can get the Xerox of the important topics.
5. If you know that none of the above ways could be applied, then you can get the important concepts of the book photocopied so that they stay with you forever. This can be done before returning the book.