As a vegan, I intend to use tofu as my main source of protein, iron and calcium. Therefore, I am concerned about bioavailability (i.e. absorption divided by intake) of iron and calcium in tofu.
As far as I know, there're two kinds of tofu, divided by a difference in their production process:
- Those treated with CaSO4, known in US/UK as "calcium-set tofu", and in China as "southern tofu".
- Those treated with MgCl2 (among other substances), known in US/UK as "traditional tofu" (not sure), and in China as "northern tofu".
These two kinds vary greatly in calcium content: roughly 300+mg/100g for the former, and 100+mg/100g for the latter. 
There had been studies on the iron bioavailability in tofu ().
However, I hadn't found any infomation on the calcium bioavailabity in traditional tofu. So, could you share your relevant experiences, or point out some relevant studies?
UPD: Luckily I've found ways to get around this problem, so answer to this question doesn't matter much to me now.
The paper is about mineral content in all kinds of common soy products in China, and it's written in Chinese.