My favourites are anything by Pinky McKay, the most appropriate probably being "100 ways to calm the crying". I felt empowered by her suggestions probably because she really helped me to stay tuned in to my baby. I've read a few books that are big on routine and I think the reason they work sometimes and not others is because our little babies aren't born to fit into schedules, especially when they are less than 6-9mths. Sometimes they are hungrier than others, somedays they need more sleep than others, we just have to follow their lead. Sometimes if you try to fit your baby into a routine that suits you, it can really backfire as it causes more stress when things aren't going to plan.
Get in tune with your baby, watch his/her cues (especially tired signs - jerky arm and leg movements, grizzle, yawn, rubbing eyes, etc.). My two children were both very different as babies. When my DD was 5mths (now 2 1/2years), she was ready for bed within 2 hours of waking up. If I got her to sleep as soon as I noticed the tired signs, she would sleep for 2 hours, she would then be up for 2 hours and I'd put her back down for 2 hours. It's like there was this window of sleep opportunity and I reckon it was only about 20 mins long. If I didn't get her to sleep within 20 mins of seeing a tired sign (jerky movements were the best cue) she would be a nightmare. It would take me nearly 2 hours to get her to sleep and she would only sleep for 1/2 an hour and the day would continue like this.....I would be completely frazzled and STRESSED!!!! and Arnya would still be crying and screaming.
My DS, now 10mths, never showed any tired signs and didn't get upset if he only had 2 20min per day (which was all he got between 3 and 5mths). I found though that when I started putting him to bed 2hours after he woke up (just like I did for DS) even though he wasn't showing tired signs, he went to sleep easily and began to sleep longer in the day. By 6mths, he was having 2 regular 2hour sleeps and still does. Up for 2, down for 2, up for 2, down for 2, up for 3-4hrs (dinner, bath, breastfeed), bed for the night. That's our routine that has worked for both babies, but probably because the babies demanded it....I just listened.
I wish you well and hope you get lots more sleep out of you little ones. Remember to stay in touch with them....they are intuitive little beings that know what they need and only know one way to ask for it. Happy mummying.