1. Academic database: This is the most important way to obtain academic papers. Commonly used academic databases include PubMed, WebofScience, Scopus and CNKI (China Knowledge Network). In these databases, you can enter the keyword "enzyme" or a more specific enzyme name, such as "α-amylase", and then filter out relevant papers. The references section of these papers usually lists other related papers cited by them, and this is the second-hand reference you find.

2. Professional journals: Many enzyme studies will be published in professional journals related to biochemistry and molecular biology, such as JournalofBiologicalChemistry and MolecularBiologyoftheCell. You can search for related papers on the websites of these journals and then check their references.

3. Books: Some books about the basic theory and research methods of enzymes are also good reference sources. You can find these books in the library or online bookstore, and then find related papers in the reference section at the back of the book.

4. Academic conferences: Many enzyme research conferences are reported and discussed at academic conferences, and the proceedings of these conferences are also a good place to obtain reference materials. You can find these papers on the website of the academic conference, and then check their references.

5. Expert recommendation: If you are particularly interested in a specific enzyme or an enzyme in a certain aspect, you can consult an expert in this field. They may recommend some reference materials that they think are important to you.

The above are some ways to find references for papers on enzymes, hoping to help you.