One of the things I own is a letter from Tsarevich Alexander (future Alexander III) to a Count Ivanovich in 1870. The letter is written in the hand of a secretary, but is signed by Alexander:

A translation is as follows:
Count Alexander Ivanovich. In the past year, doctors found it necessary to take my children to the sea this summer, and when in March the place of residence was supposed to be selected on the Baltic Sea, I suggested Gapsal, as a place not only beneficial for health, but also the place, which left the most gratifying memories thanks to, of course, the time spent at dacha, which Countess de-la Gardi, who passed away, used to place at our disposal without fail.
Grand Duchess and I, as we found out about your willingness to offer us your home for the next summer as well, were anticipating the benefit and pleasure of staying there, but God wished to test us, what forces us to refuse your kind offer: it is impossible for Tsearevna to go to Gapsal alone; I, due to my military service, have to stay at camp; that is why we decided, that she and our son will set off for Denmark, where, as doctors assure, staying at the sea will be just as beneficial for the child; and the Grand Duchess will find consolation in her sorrow amongst her family.
Thus, we apologize to you and Countess for inconvenience, and ask you to kindly extend your hospitality, if next year our son has necessity to spend a summer in Gapsal.
Please convey to the Countess deepest regard from me and Tsesarevna.
With sincere respect and gratitude,
Yours Alexander.
The 10th day of May, 1870
Tsarskoe Selo