IMHO, making a quilt you found in a book or magazine for your own personal use it allowed, otherwise, why would they be published for you to see? If you will be displaying or entering it in a show or contest, then by all means, give credit where credit is due. Things change completely if you are making to sell. Then you must be attentive to copy right and design infringement.
That said, I get most all my inspiration from books checked out at the library, or from free you tube videos. If I see a pattern that really grabs by attention, then I will buy it, but so far have not used any of the patterns I have bought. A lot of 'patterns' I have seen, are really just creative fiddling with the old time public domain patterns anyway. The art quilters are so far advanced beyond my capabilities, that I not only would not be able to replicate their work from memory, but doubt I could do it following a pattern either. So no worries there.