Am I using WROX Android Application Development, which recommends using the android 2.3 api 9 revision 1 platform?
I noticed that it does not appear in the Android SDK Manager. My smartphone uses Gingerbread and what it needs.
What are my options?
API level API 9 is deprecated and replaced by API level 10 (which is still 2.3, aka gingerbread).
You can show it in the SDK manager by clicking the "deprecated" checkbox below, but you should use API level 10 instead.