Bibliography (6):

1. BART: Denoising Sequence-to-Sequence Pre-training for Natural Language Generation, Translation, and Comprehension

2. BERT: Pre-training of Deep Bidirectional Transformers for Language Understanding

3. RoBERTa: A Robustly Optimized BERT Pretraining Approach

4. GLUE: A Multi-Task Benchmark and Analysis Platform for Natural Language Understanding

5. Wikipedia Bibliography:

   1. ROUGE (metric)

   2. BLEU