What are the key steps involved in implementing the external merge sort algorithm for sorting large datasets stored on external storage devices?

The key steps in implementing the external merge sort algorithm for sorting large datasets on external storage devices are:

1. Divide the dataset into smaller chunks that can fit into memory.
2. Sort each chunk internally using a sorting algorithm.
3. Merge the sorted chunks together using a merge process that involves reading and writing data to and from the external storage device.
4. Repeat the merging process until all chunks are merged into a single sorted dataset.