Because the question asks, "which sources say yes and which sources say no", I feel like the question warrants a response that includes a few more sources. The most comprehensive discussion of the issue is published by Dr. Ari Zivotofsky in Bar Ilan's journal Bechol Derachecha Daeihu (vol. 19) and its history is summarized in this news article.
Rav Hershel Schachter (Divrei HaRav p. 192) insists that there are no specific rules about what the scales of the fish should look like in order to be considered kosher scales (as in, scales that are a sign that the fish is kosher), but concedes to the fact that the swordfish has unusual scales in that the scales are attached on both sides. He quotes his teacher, R. Soloveitchik, as allowing the swordfish despite its unusual scales for this reason.
However, R. Tendler points out (Pardes Rimonim, p. 106-112) that there are requirements for the nature of the scales: the Ramban on the Torah (Vayikra 11:9) states that the scales must be easily peeled off, and not fully attached, as is the case with the swordfish. R. Tendler insists that this has been the accepted halakha for centuries: the Magid Mishnah in the beginning of Hil. Maachalos Asuros, and the Rama in Shulchan Aruch, Y.D 83:1. To top it all off, R. Tendler states that R. Y.D. Soloveitchik agreed with him (and not as stated in Divrei Harav, above) that the swordfish should not be eaten.
The Kensses Hagedolah also writes (Y.D. 83:74) about a fish with a sword on its nose that it's kosher, though R. Tendler insists that he is referring to a different fish. Several fish of this nature are discussed by the Pischei Teshuvah (Y.D 83:1), where he also adds that if such a fish is kosher, then there's no reason to prohibit this fish on the basis that it looks like non-kosher fish, because it looks like a kosher fish - i.e. it has scales.
As in America, Israeli Rabbis also disagreed on this issue. Rav Unterman, chief Rabbi of Tel Aviv, wrote a teshuvah permitting the swordfish (Shevet Miyhuda vol. 2, 5:118) based on the fact that there was a widespread and ancient custom to eat such fish, while the Tzitz Eliezer (9:40) prohibited it, based on the Ramban and R. Tendler's research.
Interestingly, R. S.R. Hirsch, in his commentary to Vayikra 11:9 also insists that the Ramban's interpretation has been accepted as the halakha, despite, he adds, the fact that the Noda Biyhuda (Tinyana Y.D 28) seems to argue. (In reality, the Noda Biyhuda agrees on principle but believes that scales that can be separated from the fish by any means are kosher, not just if they can be peeled off easily or from one side.)