1. Tirmidhi in Sunan→3 hadiths
2. Abu Dawud in Sunan →8 hadiths
3. Ibn Majah in Sunan →8 hadiths
4. Ahmad bin Hanbal in Musnad →12 hadiths
5. Abd al-Razzak ibn Hammam in Al-Musannaf →8 hadiths
6. Ibn Abu Shayh in Al-Musannaf →14 hadiths
7. Ibn Hibban in Sahih →7 hadiths
8. Haythami in Zawaid →20 hadiths
9. Suyuti in Al-Jami al-Saghir →8 hadiths
10. Al-Muttaqi al-Hindi in Kanz al-Ummal →59 hadiths
11. Al-Haqim in Mustadraq →12 hadiths
12. Al-Firdaws in Daylami →7 hadiths
13. Al-Daraqutni in Sunan →1 hadith
In these sources there are 159 trustworthy hadiths regarding Hazrat Mahdi (as).
Besides, the following great Islamic scholars included trustworthy hadiths in their works.
Ibn Qasir →3 hadiths, Al-Busuri →2 hadiths, Zahabi →5 hadiths, Munzuri →1 hadith, Azimabadi →6 hadiths, Albani →6 hadiths.
These are only a portion of the trustworthy hadiths regarding Hazrat Mahdi (as). Apart from these there are many other trustworthy hadiths and explanations regarding Hazrat Mahdi (as).