Many landscape architects maintain a website through the company or university they work for. These are great sources of information on their inspiration, backgrounds, and projects.
Professionals are often glad to talk with students by email. If you have questions about an individual's work & haven't found the answers through your research, consider contacting him or her. If you do so, make it clear that you're a university student working on a project. Also make it clear that you've already become familiar with his/her work and that you've done plenty of research already. These factors give you the best chance of receiving an answer (based on past classes' experiences).