"Are contained in" is a commonly used phrase to express the idea of something being inside or within something else. There are several synonyms for this phrase, which can be used to add variety and depth to your writing. Some alternatives include "reside in," "can be found in," "are situated within," "are enclosed by," "are housed in," and "are embedded in." These phrases can help make your writing more dynamic and engaging, while also expressing the same basic concept. Choosing the right synonym can depend on the context and tone of your writing, but these options provide a starting point for adding variety to your vocabulary.