You can talk about the Guhyasamaja and the Guhyagarbha topic as much as you like. Very hard to get well structured studies on these in English. HH Kyabje Zong Rinpoche's commentary is the best I've found so far. I think one day someone will rediscover these lost treasures and retranslate them into different tongues with loads of passion - probably not in our lifetime though, but some day.