The phrase "a third thing to" is correct and usable in written English.
It can be used when introducing an additional item or concept in a list or discussion, typically following two previously mentioned items.
Example: "We need to consider the budget, the timeline, and a third thing to ensure the project's success."
Alternatives: "an additional aspect to" or "a further point to".
Federer had already passed Roddick with power topspin backhands cross-court and down the line; now, with this delicate lob, he completely off-footed him, and Roddick was then forced to face a terrible truth: there's a third thing to worry about when you come to net against Federer.
But then it is a third thing to acknowledge a point you have drawn from another -- assuming, of course, pace solipsism, you believe that there are other people in the world, and they might possibly have something to say.
A first thing to notice is that the number of email addresses is three times bigger than the number of phone numbers, emphasizing the facility to acquire mailboxes for malevolent purposes.
A first thing to note is that the cross covariance M k in the KF and its ensemble equivalent ({bar {M}}_{k}) should not be influenced by additive measurement noise e k.
So perhaps there's a sixth thing to watch for during oral argument: which justices remain silent?
At the next layer, what I have labeled a mature elder, we discover we are still giving our power to a second thing, an outside belief, when we no longer believe there is a second thing to receive our power.
A first thing to note from the figure is the composition of the experimental foods (filled squares for wet foods and hollow squares for dry foods).
A first thing to note is that the presence of auditory nontargets can result in both longer and shorter perceived visual durations, depending on the relative duration of the nontarget sounds.
"But I then said to the pope: 'There's a third thing I want to ask you.'".
The pursuit of happiness is then assumed to be a third thing: my unfettered ability to amass property or good experiences or cherished possessions.
