From Pearce, J. W. E. 1901. The Agricola of Tacitus. London: George Bell and Sons. Pp. xi-xii.
The following references to the Letters of Pliny, which are addressed to Tacitus, may be interesting:
1.6. Tacitus is not to laugh at Pliny's habit of taking note books on a hunting expedition. Tacitus may do likewise when he goes hunting.
1.20. Pliny asks whether brevity is advisable in oratory. He wants a letter from Tacitus to convince him.
5.13. Tacitus is to look out for a teacher for Pliny's native place from among the number of literary men whom his talents attract to him.
6.9. Tacitus asks Pliny to help Julius Naso's candidature.
6.16. The story of Pliny the Elder's death in the eruption of Vesuvius. Tacitus has asked for it in order that he may give a true account to posterity. Pliny says the story will be immortalized by Tacitus.
6.20. Pliny tells Tacitus at his request the story of his own escape from the eruption.
(xii) 7.20. The literary brotherhood of Tacitus and Pliny. They will always be mentioned together. Tacitus was maxime imitabilis, maxime imitandus by Pliny when a youth.
7.33. Tacitus' histories will be immortal. Tacitus is asked to insert an episode in which Pliny showed to advantage in connexion with the prosecution of Baebius (cf. Agr. 45.1).
8.7. Tacitus has sent a book to Pliny for his criticism. Pliny says that he is the discipulus, Tacitus the magister.