Our eTextbook is browser-based and it is our goal to support the widest selection of devices available, from desktops, laptops, tablets, and smartphones. We constantly test and work to improve our eTextbook compatibility on as many devices as possible. We recommend that you upgrade your browser to the latest version and we encourage you to test and preview our eTextbook on your device before purchasing.

Please ensure that your code is being entered correctly. A common issue is the confusion of certain characters. We tend to see capital "I's" as in Iowa confused with lowercase "l's" like leopard and/or the number "1".

Our access codes do not contain lowercase "l's" (leopard) or the number "1"; in these cases, please use a capital "I" (Iowa).

Another reason may be that you have a used textbook and the code is no longer valid. You can purchase course only access on The MIT Press.

If none of these examples represent you, please submit a ticket with a picture of your access code and we will further investigate the matter.

The most common problem we see pertains to the following message: Street Address does not match (N). Postal Code does not match (N).

This indicates that information on file with an issuing credit card company does not match what is entered. We typically see this occur with individuals who have moved recently or individuals using a school address instead of a home address.

Our advice is to contact your financial institution and verify the correct billing information. You may want to ask about any failed transactions and inquire as to the status of those funds.

Please submit a ticket if you think that this is not the issue.